The Pass Labs INT-25 Integrated Amplifier Review. The Sweetest Perfection.

The Pass Labs INT-25 Integrated Amplifier Review. The Sweetest Perfection.

By Steve Huff

Also, see my Pass Labs INT-250 Review HERE

Video Review

The Dream

It’s been about 20 years. Twenty years of wanting to either own or evaluate/review a Pass Labs amp. I never had one in my home but have heard them in other systems and at a show. Having read for so many years the attributes that this legendary brand of audio brings to the table, it always sounded like it fit right in with my musical tastes. Warm yet Rich. Detailed and Textured yet never bright or hard sounding. Fluid and Full without a hint of strain. Muscular and huge sounding yet delicate when need be. What is not to like about those words that have described the Pass Labs sound over the years? Today Pass Labs offers up three choices in the INTEGRATED amp space. This starter lowest cost INT-25 (Class A) which is what I will speak of here, the more powerful INT-60 (Class A and A/B) and of course the massive $12k INT-250 (Class A/B) which is considered by some out there to be the finest amp they have ever heard.

Such a Handsome Piece of HiFi – The Pass Labs INT-25

Nelson Pass, the genius behind the amps and the Pass Labs/First Watt names is highly respected in the audio biz, and for good reason. Some of his First Watt brand of amps are considered legends in the world of audio. While they may not be like most modern day uber hyper realistic and surgical detailed amps, I have always read that these amps sound more lush, warm, muscular (remember that word), expansive and 3 dimensional yet with details air and spaciousness intact. I have read over and over that these Pass Labs products have some kind of special mojo about them.

Seeing that I recently reviewed a $1299 tube amp that is made in China and declared it a massive “Bang for the Buck” product (and it drove my Heresy IV’s very well) I figured it would be a good time to review an integrated that is said to sound more like tubes than most solid state amplifiers, and I will even compare it to the tubes I have here. The interesting thing here is that the Pass Labs INT-25 I am writing about costs a cool $7500 brand new (retail), much more than the $1299 tube amp. With that said, the Pass Labs is made in the USA, and by a company who has a long track record of performance, success and know how. They are highly respected and while their sound signature is not loved by everyone, for others it seems it is the perfect sound they have always searched for. It seems with Pass Labs there are two camps. Those who buy and would never sell as they found their perfect amp for life and those who buy and are not fans of the Pass Labs sound, and move on.

Btw, before I go further this is not going to be a technical review. I do not do or even believe in measurements for audio gear or photo gear. For photos, my eyes are the judge and that is all. For audio, my ears are the judge and that is all. It’s what I see and hear that matter, not what a measurement tells me. So if you want to see these things, I suggest reading the stereophile review HERE.

When I was 16

Before I get to the meat of the review, or even speak of my thoughts on the INT-25 I would like to talk about my younger days in audio/HiFi for a brief moment.

When I was 16 (35 years ago) I was heavily into music and stereo systems just as I am today. Even back then (1985) I lusted after higher end stereo gear though it was not as easy to come by as today, nor could I afford it anyway. Without internet, smart phones or any real mail order shop for HiFi I was only able to shop locally. For me and my 16 year old self who had a crazy limited budget that meant local electronic chains like Silo, Highland and others. Of course only after months of saving. This was even before Best Buy, circuit city, etc. My choices were limited to the gear they carried and what I could afford. No way I could touch a boutique shop, if one even existed near me.

When I did finally assemble a system in 1985 it was not a very good one by today’s standards, but back then I thought it was the best thing ever, and I loved it. It played loud with it’s 100 watts per channel amp, and I only played records back then. Each week I bought one new album and enjoyed listening all weekend long in my room. What I remember about the sound during those times was that it was loud, had serious heft to it, and could shake the room if I wanted. It had no imaging, no 3D, no air…I didn’t even know what that stuff was at that time. It was just pure direct pumping ballsy energetic sound but I LOVED IT then. It is the sound I grew up with.

As I grew older and started to assemble my first real serious system at 22 years of age, after having much more knowledge of audio, I was very unhappy with what I was hearing, especially since I spent close to $10k on that first system (compared to the $895 of my old system from my teen years). It sounded thin, had no weight, and sounded “broken” yet it did have hyper detail. When I went back to the shop to ask why this was, I was told that is how a real “audiophile” system sounded without bloated bass. WHAT?!?! I was told I needed $2500 RCA cables to make it a little bit better. There was almost no bass to be found in these $5500 tower speakers. I didn’t understand it then (but today I do). At that time many high end brands were voicing their amps and pre amps to sound uber detailed, and with extreme imaging. To get there, the high frequencies prevailed over the low. To me it made music sound thin, sterile and broken. If that was high end, I did not want it.

It seemed easy as all I wanted was a big sound, with clarity, sweetness, depth, some transparency and details but with bass, mid bass and a full complete sound. I did not want thin, analytical or bright. I knew it had to exist but damned if I could ever find it. In fact, it took me many more years to find a sound I really loved with higher end gear.

A Sound Demo of the INT-25 and Heresy IV. Keep in mind you can NEVER hear what it sounds like in my room via video, as 90% of the magic is gone in a video. With that said, you can get an idea of the character of the sound in the video. The Pass is muscular yer refined. Tangible and Sweet. Holographic and with amazing Depth. The perfect match for Klipsch Heritage IMO. In my room, this surpasses any integrated amp I have owned or tested in over 20 years. Not sure what magic Nelson Pass has discovered but whatever it is, it’s pretty remarkable. 

That sound eventually came in the from of a pair of Cary Audio 805C single ended mono block tube amps when I was in my 30’s, paired with a Cary SLP98P pre-amp and a Cary 306/200 CDP and DAC. Speakers were older Sonus Faber, which had the reputation back then for being warm and romantic. While it was much more refined than my old teenager setup, it brought me that depth, the fullness, the liquid sound but without sounding anemic. I remember sitting back saying “wow, this is AMAZING”! Then I said “wow, it should sound amazing since I just spent $18k on a system”!

I lived with that system for a while, and it was only when a life emergency entered into my life that I had to sell it all. I was upset, but I knew I would one day in the future have a nice HiFi system again. When that time came I decided to try new things. New modern amps, and digital front ends that were supposed to be the best things ever. Again, just as before, I found a lot of brightness, thin sound and hyper detailed speakers and amps.

I admit, I did fall into that sound for a while, seeking hyper details and extreme imaging performance but over time it got boring and fatiguing, and I realized that I swayed from what brought me to HiFi in the first place. Music that sounded like Music! I started to lean back to a more musical, warm and fluid sound over the last couple of years and its is so much better for my ears. Today I am all in on the “musical” sound with depth, texture and some warmth and have been seeking it out in a few ways.

Fast forward to right now in 2021. Many years since those early days of my audio journey. Over the last year (2019-2020) I have reviewed quite a few audio products. What you guys do not know is that I have had more than double of what I wrote about in my home, but half of it was sent back without review as I thought they were overpriced, or didn’t offer good value. Again, I only review what I love and what I would recommend. That goes for camera gear and audio gear. Many like to say I love everything, but that is not the case. What I love, I write about. What I do not, I send back without mentioning it. Not worth my time to write negative reviews. But when I adore a product, I get excited and write. I also buy quite a few pieces and I have sold many of them as the new comes in. I love trying new gear, new brands and new things with audio but this is changing.

I am getting older. Now in my 50’s I am slowing down. I am feeling more relaxed and less stressed. I am happier. I am at peace. I have much more patience than I used to have. I am nicer, calmer and more understating. I do not let things get me down. I am more easily satisfied with everything in life and do not feel the need for always having to try the newest thing.

I am getting to the point where I want to “settle down” with my audio system. Lock it in now that I have moved for the last time in my life (I hope). Now that I have a new dedicated audio room. I just want to have a solid long term system and I have been working at it for the last couple of months. A reference for future reviews and comparisons is what I needed, from speaker to amp to source.

The hardest part of this goal has been to find the perfect amp within a budget I set. I wanted an Integrated and I wanted a sound that leaned warm, rich, but still retained a huge room filling soundstage and details, depth and natural imaging without going over $7000. I didn’t want muddy or dark, just cozy and an inviting listen with hopefully some magic thrown in for those quiet nights of listening. 

What I have chosen so far as of Jan 2021 for my solid long term system. These pieces are locked in!

After hearing countless high end speakers in my life my final pick for long term enjoyment is the Klipsch Heresy IV. Yes, I prefer them to all other speakers I have owned, tested or borrowed (over the last 30 years) and that thought has stuck since they have been released about one year ago. Not because they are the most revealing, detailed or sharp..but because they are the most musical, live, inviting, warm and huge sounding speakers I have heard (I prefer them to the Cornwall IV). They are never bright, shouty or fatiguing when used with the right amp and source. Rather they are big, warm, rich and very 3 dimensional and yes, they can put out some bass with the right amp (and some amps will make these sound thin and bright, as they are chameleon like and react highly to your changes in gear).

My digital source? I am 100% thrilled with the Bluesound Node 2i, even after owning much higher end Digital sources like a PS Audio Direct Stream or Zen Mini MKIII and the Phoenix. When used with an external DAC it’s just as good as big dollar streamers I have owned.

For DAC duties I am sticking with my fave from the last two years, the Chord Qutest. I added an Mscaler as well, and after that there is no looking back. See my review of those pieces HERE.This is the finest digital front end I have ever owned or heard. It’s truly one of the most important aspects of this system. What it does to the system is just as striking as a speaker or amp upgrade and even when I tried to remove these pieces for comparison, I rushed to place them back in. They are excellent.

I love my cables and have had them in place for a while now. As for the amp, I have had a couple here ever since I had to let go of my VR L2i SE. I now have a Naim Nova and it does kick serious bootie and is an all in one, and easy to use. The Willsenton R8 Tube Integrated (still own) is an incredible bang for the buck and punches well above its $1299 price. I have a China made 300B amp here as well ($800) as the little Reisong A10 teeny tube amp that is Class A but only 10 watts ($425). As you can see I have been testing out all kinds of integrated amps lately yet none speak to me within and said “THIS IS IT” when it comes to looks, price and performance. All three must be there. I did not want a $20k amp nor an ugly one. Call me superficial but if I am spending $5-$8k on an amp, it has to look good too.

Even though I love the Willsenton (and it bests the 300B amp and A10), I had a feeling I could get better but of course probably at a big big cost. What I was lacking in the R8 in this setup was really with rock music… the sound was just not beefy enough and could get thin sounding with the H4’s when playing rock or aggressive music. There was a lack of big impact and mid bass causing these types of songs to sound slightly hard or thin. The R8 tube amp can do impact but that is not its strong point. With vocal and Jazz, gorgeous. With rock, metal or hard music it didn’t have the gusto to fully flesh out the Heresy IV’s. So what could do better I asked? How much would it cost me? Sure I could go back to amps I have had in the past but where is the fun in that? I knew I have always wanted to try a Pass Labs amp and upon research I found one that looked like it fit the bill perfectly.

Class A is SWEET

I now have been evaluating the Pass Labs INT-25 which offers only 25 watts of Class A power per channel. Plenty for my 99db efficient speakers (and class A brings such a sweet warm sound) and even those Q300’s that are not that efficient sound glorious with this amp. I love/adore/cherish Class A over A/B or D. Class A amps have a rich organic quality about them. The Luxman 590 AXII and Line Magnetic 219ia were both Class A, which is why I adored them as I did. This Pass Labs is also a Class A design. It gets hot, and can be costly to run for days on end (electric bill) but the sound Class A brings is as premium as it gets for these ears. On standby the amp barely uses any power, something like half a watt but they say that the longer these Pass amps are on, the better they sound.

So how does this very pricey $7500 retail Pass Labs fit in to the picture? Let’s talk about it.

When the Pass Labs INT-25 arrived from Moon Audio I knew I had a 30 day period where I could evaluate and return if it did not sound good in my system, and I was ready to use that 30 day period and return this amp if it did not bring a large improvement over the R8. Honestly, I did not think it would warrant the extra cost.

After spending weeks researching if Klipsch and Pass mesh together well I really found NO REAL CONCLUSIVE INFO! So I went in blind, and the amp arrived two days after I ordered. Well packaged and all arrived safe and sound.

I removed the Willsenton R8 and placed in the INT-25. Knowing it would take about an hour to warm up and sound its best (as per the manual and what almost everyone who owns a pass amp says), I left it running on low volume (which if I can admit, sounded rather special already) for a couple of hours and when I returned I settled in and pulled up a few tracks I was very familiar with via Tidal using Roon.

The First Listen

Using ROON I pulled up “Breakers Roar” from Sturgill Simpson. From the first few seconds I knew this was going to be a special amplifier. When I reviewed the Willsenton R8 I talked about how it brought some warmth and a fuller midrange sound to my Heresy IV’s (with EL34 Tubes vs KT 88) compared to the Naim Atom/Nova. What the Pass Labs amp did was up that by a factor of 5 but also added a natural sweetness, fluidity and texture to the sound that was oh so lovely.

This is a very midrange-centric amp. It is king of the mids….as in drool worthy mids. I can say without mount that this amp has the best midrange performance of any amp I have heard. It’s really special. Silky. Sweet. Big. Rich. Textured and at times haunting. Voices are surreal.

With the INT-25 powering the H4’s I now had a fully effortless liquid sound floating from the speakers but with even more body, more heft, more weight and more warmth. The key here is that it did not sound the slightest bit veiled, muffled or syrupy. Rather the vocals were the biggest and largest I have heard them in this room. Pure. Magic. The instruments were detailed and while not intense with imaging, it was just about perfect as the music sounded complete, whole and missing nothing.

What I heard was a surreal 3 dimensional floating voice dead center as Mr. Simpson croons and sings with a velvety smooth voice as instruments swirl around the room with a velvet glove on. The instruments are also presented with authority, heft and air. Romantic maybe?

Yes, I want to say Romantic but do not take that in any way as being dark, or overly warm as that is not what is happening here. In fact, for these ears it is just what the doctor ordered. For example, when I cued up KISS Alive II it took me back to when I was 16, jamming to the vinyl in my room. It was big, ballsy, had such a full sound with warmth and it sounded LIVE but without any hint of being anemic or thin or bright or flat. It took that sound I remembered but enhanced it greatly with details, a very deep soundstage (more deep than wide) and such a magical midrange. Could this be THE sound I have truly been searching for my entire life?!?!? I was able to FEEL the bass from the Heresy IV’s and I do not use a sub. The bass performance here bests any integrated I have had. The midrange bests any I have had. The highs are slightly toned down, which assures you will never feel fatigue. They are there and present enough to add magic and air but not more than that.


I cued up a song that I knew was slightly thin sounding with the Naim and then the R8 powering the Klipsch. From Karen Daltons album “In My Own Time” I cued up the track “Are you leaving for the country” and heard her voice in a way I never heard it before when played with the INT-25. With other amps, her voice was a bit thin and could sound a tad grating at times on this album. With the INT-25 it was like liquid velvet. It was so enjoyable, musical and free flowing that I just sat and listened, and then listened again. As I said a big “WOW” to myself I wondered now how this compared to the R8 side by side as that R8 is a fantastic amp that sounds better than it costs.

After 3 hours of solid listening to the Pass Labs I brought the other amps back in and what this did was tell me all I needed to know. I will just say it now, but like one other reviewer has said about the is a bargain at $7500. I will state why in my conclusion but the other amps I have here did not get close to what the INT-25 brought to the table when listening to them side by side. Each has a totally different sound signature as well.

While the INT-25 is not the most detailed, crisp, nor the king of imaging it has something about it that is scary good “magical musical”. It’s that smooth velvet like presentation but while retaining a nice big deep and tall soundstage with impressive width as well. There is detail there, it is just not in your face. It melds perfectly with the rest of the music to make a complete picture. It is whole. It is like a big tall glass of plain 2% milk vs a glass of water but it is making the most beautiful music in my new room. Besting the R8 and Naim with the Klipsch Heresy IV easily and with quite a bit more refinement than the R8.

Leonard Cohen’s “Going Home” is spooky real with the INT-25. His vocal is so hefty, rich, throaty and REAL. As if he is telling a story just to me as my lights are out and all I hear is a beautiful song while envisioning him right there in the room with me. If any of you have this amp and Klipsch Heritage speakers, cue this track up in the dark. It’s an experience.

This INT-25 sounds like no solid state amp I have ever heard.  As good as the lower cost R8 was in this setup, and it truly is phenomenal for the cost, the Pass took it up a quite a few levels into an area I have not experienced before with the Heresy IV’s.

The huge upside here is that the INT-25 is solid state, so no maintenance of tubes, yet it sounds better than the tube amps I have here. It’s built like a tank, and to the same level as something like the drop dead gorgeous Luxman 590 AXII. Just a different more utilitarian, yet sleek and sexy look. It’s a gorgeous amp, and heavy as well at around 50-60lbs. It has only what you need and nothing you do not. No meters, no phono stage, no DAC. Just an analog two channel high quality integrated amplifier with three RCA inputs.

It is simple but it is also liquid. It’s 3D. It’s warm and rich and has texture for days. It fills the room with ease and a soundstage so deep, I feel as I can step up and walk into it (I even tried this one night and it was spooky). It’s a little romantic, and produces females vocals with such a beauty, it makes something like the Naim sound like it has a thin sharp midrange when I compare side by side, and that is crazy to me!

It’s amazing how some audio pieces just speak to you. While I can not say this is “the” amp for all speakers or ears, for my speakers and room and upstream gear it 100% is. In fact, this will be my long term reference going forward. It will be used to judge all others that may come in for review. 

Do you want perfect measurements or to hear amazing beautiful music? 

Pass Labs amps do not always measure perfectly. It’s the way they are designed, and have certain kinds and small amounts of harmonic distortion that brings more appealing and beautiful (imo) sound. I have had “accurate” amps and most of them sounded fatiguing after a while. Some were superb but sounded boring or sterile after a while. What this tells me is that measurements are not important to me in the real world of listening to music with my ears.

What my ears hear will always trump “measurements” and this is the most musical and real sounding amp I have heard in my life. It has MUSCLE (there’s that word again). Most amps do not have this kind of MUSCLE and in fact, this 25 watt class A amp has the most muscle of any amp, regardless of watts, I have used or owned.

You may hear words like this to describe pass amps from other reviewers and they are right. For me it is the muscularity of these amps that make what we hear through them so special. I know I can cue up Billy Idol, Judas Priest, Jewel, Diana Krall, Miles Davis, Mac Davis, The Cure, Dolly Parton (and everything in between) and have it sound so damn good in every way. 1970’s, 1980’s. 1990’s music? Bring it on. Yes, this does wonders for your older 80’s recordings. It will not make then perfect but what was unlistenable on one amp is now beautiful on the Pass. This does not mean they sound bloated or thick, they do not. I can not put my finger on it but the sound here with this INT-25 is very addicting.

There is nothing cold, analytical, bright, fatiguing or harsh about the INT-25 wether I listen at low late night volumes or rock out. This is amazing at low volume with the Heresy IV’s. For me it strikes the perfect balance between warmth and detail. Luckily for me the Heresy IV’s live in the mids. This amp makes them punchy, impactful and sweet. They do lose out on some all out sharp sounding dynamics (especially compared to the Naim) but the heft and impact for me beat dynamics, and besides, there are still a ton of dynamics on tap here. It’s astounding really how this pairing sounds. It’s what I would call a Heresy IV “Dream Amp” ; ) I do not believe there is a better amp to pair with modern day Klipsch Heresy Speakers. 

It’s the sweetest perfection for my ears and gear. Nothing is offensive, rather it is appealing and draws you in, sucks you in and the only complaint in my house may be from Debby as I am now in a state where I can not stop listening to music!


Some may wonder what I think of the INT-25 compared to the Luxman 590AXII which is another beautiful heirloom quality integrated that comes in at around $9000. I could live with either but I would be happier with the Pass with my current speakers. The Luxman is more detailed, and has a thinner mid bass. With the Heresy the Luxman sounds a bit thinner and lacks the warmth and glow of the Pass Labs. It lacks the humanity of the Pass Labs and is not as “muscular”. While superb and well worth the cost, the Luxman Class A sound is a bit different from the Pass Labs Class A. If you have warm speakers, or something like a Dynaudio Special 40, the Luxman would take the prize. With a speaker like mine, the warmth and body is welcome. Both are two of the best integrated amps I have ever heard but are on the opposite ends of the sound spectrum.

Compared to the L2i SE, the INT-25 actually has more muscle, more warmth and more glow over the big Vinnie. The L2i SE has a more clean sound, and digs into the details a bit more with super refinement and silence, and brings out the highs more. This amp is amazing with something like the QLN Prestige 3’s. But this shows how important system matching is. The Pass is superior with the Klipsch speakers, and by a nice margin. The Vinnie is superior with harder to drive speakers and retains composure even with harder to drive speakers. It’s refined as can be and a gorgeous end game amp, much like the Pass.

Compared to my fave tube amp, the 219ia the INT-25 has much more in common than not. The sound signature is quite similar but the Pass Labs has that one thing that makes it better for me…the “muscle” and no maintenance. It’s the way the Pass Labs can sound like tubes without the maintenance of tubes while adding more texture and bass. Rich, warm, intimate, real and 3 dimensional. If I had to choose one, it would be the INT-25 for the reasons of simplicity and no tube costs. They do not sound exactly alike but again, are more similar than different. I’d say the INT-25 is more refined and smooth.

The INT-25 is also dead silent. No noise from the amp, or my speakers when idle. It has three inputs, single ended (not balanced) and that is it. The huge all metal remote is beautiful as well, and controls volume, mute, power and input. You can also turn off the volume display via the remote if listening at night, in the dark. I have to say my friends, this amp is a stunner. I feel drawn to listen to it every day.

Who is this For?

This is an amp for those who want a richer, bigger, more muscular and refined sound in their system. If you find your system sounding thin, or harsh or weak with bass or drums, or even too bright in the highs then a Pass Labs INT-25 could be your ticket to dreamland. Of course this is a 25 WPC Class A Amp but Pass amps always are conservative in their power output ratings and usually can power speakers that are harder to drive. Even so, this amp with an efficient speaker is magical. If you enjoy your midrange, or vocals and want them to be as real as you can get, I have never heard them more real then with the INT-25. Let’s not forget that while it is a simple design it is gorgeous in the flesh. Much better than the photos make it appear. It’s a true heirloom quality piece.

If “rich harmonic texture” sound like a better phrase to you than “pinpoint imaging” you may love this amp.

It’s Built to Last

One thing I love about the Pass Labs amp is its made to the highest standard, has a great warranty, and Pass Labs is known for their fantastic customer service. These amps are said to rarely EVER fail and it is said that if you have an issue, turn around is so quick as they rarely have a break down of a Pass Labs amp. When you add it all together, the price of $7500 does seem reasonable and well worth the cost for a piece that is so well designed and built.

I know that I would have a VERY hard time living without the Pass now that it has been playing music in my room . While it will be my new reference, I will keep the R8 as well for comparison sake with other tube amps. The Naim will be in my second system.

Final Word: This is one of the best integrated amps that I have ever had the privilege to listen to. The INT-25 offers me my own “Sweetest Perfection” and endless nights of fatigue free beautiful music. It can do it all from jazz, vocals, chamber, rock and roll, metal, hip hop, electronic and everything in between. If you have the desire, the funds and the passion for audio you would be doing yourself a dis-service not to check out one these integrated amps from Pass.

TRUTH TELLING:  I feel it is THE DREAM INTEGRATED AMP for Klipsch Heresy IV’s as it truly makes them sing in such a beautiful way.  At $7500 it is not cheap, but there are more expensive amps I have owned that I enjoyed less than this one. What matters for me is not measurements but what my ears hear. My ears are what measures my amps, and my ears know best for what I like. This is a true world class integrated amplifier and as one other reviewer stated, it is a bargain at its price. Drums are powerful, acoustic instruments have life and seem to breathe, vocals are magical and this amp has been measured by others to put out much more power than that 25 WPC. It will go into class A/B after 25 watts and will hit up to 65 Watts in to 8 ohms and 120 Watts into 4 ohm. There is quite a bit of juice, power and current on tap to power more than just efficient speakers. 

More Listening Notes

Octet – Chris Woods Grove Orchestra. WOW. This is so 3 dimensional with the INT-25 at the helm. Huge, rich, with amazing body on the acoustic guitar. Each and every instrument can be heard on it’s own in space and each has that texture and body that makes it sound big, powerful and controlled. I had to pull Debby into hear this and how holographic it was. This is a great demo track to judge how transparent and 3 dimensional your system is. For me it sounds so huge, deep and fluid. An amazing experience at night.

When We’re Older – James Blake. So intimate. James on the Piano with his unique voice is haunting here as he sings about moving on in death with his loved one. Starts out with piano and his voice, nothing crazy or special. As it continues the sound grows, expands and turns into an experience yet again. It then turns into a spacious presentation with reverb and a haunting ending. So beautiful and lovely as I have heard it with the INT-25. The Bass at the end? I can feel it in my seat.

Voice of the Soul – Death. This instrumental sounds pretty amazing and is recorded very well. Each pluck of the guitar strings as well as the power chord strums have depth and power. As with the others, this is presented with life yet warmth, and sounds huge with a very 3 dimensional window I am looking through. As if I can touch these guitars in the air. Again, words that come to mind is liquid, breathing, living, and a sound I can step into. Tangible is another word as the guitars sound so big and real it makes it seem as if I can grab them.

We Will Live – Linda Perhacs. This is Enya-ish. A lovely organic song that will have you deep inside swirling haunting vocals. It’s as if you are floating through the clouds and enjoying the warmth and love around you. Again, all of qualities are here. It’s truly a crazy cool 3D experience on a system that does this well.

Exile – Taylor Swift and Bon Iver. Again, what makes this amp is it’s muscularity and the way it presents the human voice. This song is all about the human voice, along with piano and it just doesn’t get better than this for my tastes. This song was a little thin sounding on the R8 and Naim, but not here. Now it sounds like it was meant to sound. So intimate, so gentle yet so powerful at the same time.

Wolf – Awir Leon. The vocal here is so real. So in the room with me. I heart crackles in the voice, breaths, and with the haunting piano behind the voice it transports you into an ethereal space. The deep bass is there, but not making itself known with bloat, rather with power and depth. It’s crazy how I hear this with these speakers but the INT-25 brings out the bass of the Heresy IV like nothing else. It completes the sound as in many systems these speakers can be thin with the bass. It’s the amp and lack of synergy that causes this. Here, the INT-25 shows it’s magical synergy with the H4’s.

I can not recommend this amp enough, especially if you have efficient speakers. If not, you may want to check out the INT-60 or INT-250 but I feel this little 25 is really truly special. This amp even makes the $400 Klipsch RP600’s sound like much more expensive speakers and powers the harder to drive Q Acoustics C300 with ease. It is a solid foundation to a high quality two channel system and it is the ONLY solid state piece I have ever heard that sounds a good as the best tube designs that exist. This seems and sounds more powerful than the Naim 70 WPC Nova. It takes control of the speakers with authority and a solid grip.

Add in the great warranty, service and heritage of the Pass Labs brand and it’s one of those “once in a lifetime” kind of things. It really is that special and not only did it bring me back to my teen years with that body and warmth but it improved on it ten fold. The question I now ask myself is…”Why on earth did I wait this long to hear or purchase a Pass Labs amp”?  If you have a local Pass Labs dealer, and are in the market for your last integrated amp ever, I suggest a demo of this INT-25. It’s magic.

UPDATE JAN 25th: I swapped out the stock power cord with my Nordost Blue Heaven cable. I listened all this time with the stock cord, but knowing how power cords can make a difference (not always better) and seeing that all of my cables are Nordost Blue Heaven I brought out my power cable and placed it in for power duties. It DID change the sound. The Blue Heaven is affordable (I have a small 1M and paid $150), and a nice upgrade over stock, or maybe a downgrade depending on your tastes.

With the Blue Heaven PC in place the sound became sharper and some of the warmth turned to more clarity in the top. It kept the amazing bass performance but brightened up the highs a bit creating a little more of that expansive sound and transparency while retaining the sound signature of the INT-25. A bit of the thickness left which meant some music lost that charm that it had with the stock cord. For me the stock cord wins here.

I also have a Moon Audio Blue Dragon power cord here that came free with the amp (I believe it is a $200 cord). When I put this cord in, it performed somewhere in between the stock and Nordost. The tipped up highs left and the warmth came back but with a teeny bit of extra life over the stock. I felt the best balance was with the Blue Dragon but the fit was a bit loose. The stock cord is made for the amp, and fits tightly and securely. Aftermarket cords fit kind of loose. For this. reason, I am sticking with the stock cable.

Either way, no matter what cord you choose, stock or aftermarket, this amp is making me smile every time I listen. I also found it does sound better after about 2 hours of being on. The manual says one hour but for me, two brings the best out of the INT-25. Sounds amazing within 5 minutes but the longer its on, the better it sounds. This is common with Pass Labs amps and integrated amps.




  1. Hi Steve,
    Thank you for your wonderful in depth review as always. May I ask if you tried these with the Fleetwood Deville speakers you have? Thanks so much. Dave

    • I sold off the Deville’s for something smaller. I now use the Daniel Hertz system I reviewed for my reviews and personal use. I still have a slew of Pass Labs gear here though I do not use it at this time. With that said, this amp would be amazing with the Deville’s and better than the XA60.8’s even (which are almost too warm for the standard devilles).

  2. …………”and this amp has been measured by others to put out much more power than that 25 WPC. It will go into class A/B after 25 watts and will hit up to 65 Watts in to 8 ohms and 120 Watts into 4 ohm. There is quite a bit of juice, power and current on tap to power more than just efficient speakers.”
    Am wondering where you came up with this? Measurements in other reviews make no mention of the INT-25 going out of Class A operation at any power level. Please provide some measurements to support your statements.

  3. I wish I could share your magical experience with this amp, Steve, but what a disappointment for me. There is a thumping sound on my speakers whenever I switch this amp on. The cones or woofers visibly jump when this happens. What damage is being caused to my speakers? And the amp is only a few days old. I have to have a brand new amp repaired… So much for the build, and meant to last for a lifetime, quality of this amp. Also uninspired by the sound. Really, very disappointing.

    • Sorry to hear this. I’ve never had that issue, at all. I would return it rather than have it repaired. Also, the sound will depend on your speakers, and more importantly your front end equipment, room and setup. I have never heard of anyone who didn’t like this amp. Could be a speaker mismatch, or there could be an issue. If you boght it new, I would return it. If used, well, repair is the only option.

  4. Excellent review. Thanks to you Steve, I have a Dynaudio Special 40, awesome speakers!. I have it with Hegel H390 but I am thinking in change it for the Int 25, what do you think about a marriage between the Pass Int25 and the Special 40?. Thanks.

    • I have not tried this but I do feel it could be fantastic. The S40’s have a great fluid and full sound, and I bet the INT-25 would bring out a more dimensional presentation. I believe Reno HiFi offers a home trial of the INT-25. Giving you time to try it, and return if it is not for you. I’d love to hear the combo myself but haven’t, so can not say for sure. When I had the S40’s they sounded their best for me with the Luxman 590 AXII which was a low power Class A Amp. I prefer teh sound of the INT-25 over that Luxman so it should be a pretty sweet match if you do not have a huge room.

  5. Steve
    Just bought the Chord Quetest and that is really good external DAC.
    Thinking about getting the Pass Lab Int25 and MScaler later. Is the Pass Lab InT25 really sounded like tube amp?
    In addition, you mentioned you bought the Swiss cables for IC and Speaker, which type Evolution or the others? Are they really that good? Where did you order them?

    • The INT-25 has some tube qualities like a 3D presentation, a full sound but with details. It’s not exactly tube like, I feel it is better : ) As for the Swiss Cables. I love them for a while, but had an issue with one of them and the build quality. This is why I never reviewed them as I felt that could have been better I build for the price. Also, I couldn’t find much info on the company. I went back to Nordost as I have always enjoyed their sound ever since they changed it up with the newer series. Thank you!

  6. Hello Steve,
    Really enjoy reading your insightful reviews on audio equipment everyday music lovers can identify with and actually aspire to own.
    I have a two part question;
    What rig did you enjoy more the Focal Sopra 2 /Mac combination or your latest Pass Labs int25/ Cornwall combination?
    Lastly, do you think the Pass int25 or the MAC would have more musical synergy with the big Sopra.

    • I have had so many systems I have truly adored in life, and sometimes when I sold them I missed them and had regret doing so. As I get older, I am tiring of the constant upgrade and buy and sell game. The INT-25 will be with me for long term, as it is truly the best sound I have had from any integrated, regardless of cost. When I say “best” I mean, for my ears, it is the sound I like. There are so many great products out there these days.

      My fave systems that I have owned (with gear that is still available):

      The INT-25 and Heresy IV with Chord digital front end. This is one that I have no desire to upgrade or change, unless I can swing for some LaScalas one day.

      The Luxman 590AXII and Dynaudio S40’s with Innuos front end. This was a great smaller room system and was one I will always remember.

      The Line Magnetic 219ia with Sonus Faber Guarneri Evolution. A special system but I preferred the two above.

      I prefer the Heresy IV to the Cornwall IV after having both for long term. But if I had a much larger room, the Cornwalls would be preferred. In a smaller space the H4’s are incredible.

    • It sure does but the A1 doesn’t excite me. Not a camera I would ever buy, and I only review what I would buy ; ) I do not review everything, only what I feel is worth recommending. The A1 is hype, includes things no one needs, and is $6500 before tax. Paying $7k for a Sony is not something I would ever do. It will not make my images or video better than what I use today. It’s a way to get hype and sell cameras but this camera is not exciting to me. At all.

  7. Thank you for doing this review Steve. I have Pass on my list to replace my circa 1988 NAD 3100. There is no way to audition Pass in Canada so it is going to be a leap I like that you put the comparisons to other amps in your reviews. It’s too bad you don’t have a few other speakers to compare.

    • Try to buy from someone that offers a trial, where you can send back if it doesn’t work for you. I would say it should be a huge step up from your NAD. Enjoy!

  8. Steve,
    I seem to remember when you reviewed the Vinnie Rossi integrated and proclaimed a lifetime purchase. Now it’s the Pass 25int. You’re starting to lose me?

    • That Vinnie IS a lifetime purchase if you can swing $26k and not feel bad about spending $26k on an amp. I had a major life change, moved cross country 2200 miles away. I could not bring everything, and needed $$ for the home purchase. I had to make a choice and have no regrets. I sold my VR as I had to at that time, along with many cameras and lenses. When I was settled back in I knew I could never swing a $26k amp again, nor did I want to spend that much again. As good as it is, it’s really out of my price league. I caved to the temptation after audition and bought it when I should not have done so. With that said it’s AMAZING if you can afford it. If I were rich I would still own it. When you can get a INT-25 for $5500 and like it even more in sound quality (and I do), then to me the INT-25 is a no brainer. I will not feel guilty for the price as what I get from it warrants the price and I could afford it. It’s really that simple. Thank you.

  9. Hi Steve,

    Great review! It is nice to see that we have similar feelings for this great amp!

    My system includes the Pass Labs INT-25 paired with the Klipsch Cornwall IVs and Naim NDX2 streamer. Speaker cables I use are the AudioQuest Rocket 88s and AudioQuest Water Interconnects.

    I could not have hoped for a more musical system. The sound is big. The sound was even better than I had anticipated as I could not audition the system in advance. I was aware of the sound I was looking for, and thanks to reviews from you and other audiophiles and music lovers, I concluded that this was the system for me, and I’m glad it surpasses my expectations.

    Though Its great for late night listening sessions, and when you crank it up you feel nothing short of listening to a live concert. I could not have hoped for a better combo that I will enjoy for years to come.

    Thank you for sharing your opinions and reviews, both audiophile and photographic.

  10. Thanks for the great review. I acquired the Int-25 in December and absolutely love it. It seems to appreciate slightly higher sensitivity speakers – my 86 dB Harbeths and 86 dB Kefs sound wonderful with it – very open, expansive and three dimensional sound. However, my 83.5 dB speakers need a little higher volume on the knob, but sound great as well at a slightly higher volume level. It’s hard to believe that a 25 class A amp could sound this powerful with such an expansive and three dimensional soundstage. I also have a couple of other integrated amps in the $2,000 and $2,500 range that I think are wonderful, but the Int-25 is head and shoulders better and in another league.

  11. can’t say much about your review, because I don’t have a pass labs to listen to, neither the H4, had though the H3 for a while, cool party boxes, lit up the neighbors well… 😉 much better than the cervin vega I had as a short interim at some point.

    But in general I’d fully agree, as to my taste it’s been all about the mids all the time, even when people focused on diamond-cristalline highs and vulcanic lows. and that’s why in the antique age of the art of theatre acoustics and public propaganda in the 20s horns and widebands were in focus. and much later at the BBC it became apparent again.

    I too am looking for a technically simplistic amp to settle in, wiped my dream of a tube-amp as none offered has the longevity or waste-regulation compliance to fit a european market (gone the ushida, shindo, … times), nor are they supportable in the context of climate-change and power consumption. gone, too, the times those items were achievable. now people brag about safety-incompliant chinese low-end price products without service. that’s not for me.
    an equally top listed dream was to own a magamp from Lundahl, but we learned quickly that Mr. Lundahl Sr.’s creation, rather interesting, was all but reliable over the following few year and most required transformers repair/replacement. Tubes & Transformers as are Capacitors are a critical maintenance item, eventually. And who’ll care about them in 10-20 years? At my place this kind of service dropped a lot to pure box sales and dealer-DIY-soldering, there it goes, as we know that on these items, repair can be destructive.

    Only a transistor or digital amplifier (I’m not mentally there, yet) can allow me to stay away from occult tubism and guru-priests of any kind “You’re not worth that equipment!”, while finding an excellent match to my phy-hp wideband salaberts and my garrard, emt, shindo, ortofon setup. is it a supernait3? a passlabx int-25? I don’t know. once the pandemic becomes epidemic I might have a shot at finding the right amp. for now, my euphyia alliance does well, enough.

    So i totally follow the improved H4 + INT-25 concept, was interested in the line-magnetic, too. But I’d love to “hear” if the supernait is still an amp to relate to, refined and subtle enough for widebands with its newer design, or if it’s a thing of the past with too many equally established but better choices out there.

  12. Pour ma part, ce sont les amplis first watt SIT qui m’auraient intéressés mais n’ayant pas les finances, je me suis rabattu sur un ancien sony ta-4650 qui possède les fameux transistors V-fet qui sont utilisés dans les fist watt SIT, et je ne le regrette pas!
    Équilibre parfait entre transparence et densité, douceur et rapidité à la fois, aucune saturation ou de distorsion audible même à fort volume, les voix sont absolument magiques, jamais mes davis OOM ont été aussi sublimées!!!

    • For me it did. Sadly. This amp sounds better than the $26k VR amp with them ; ) There’s that. With that said, I have not tried it all of course. There are so many integrated amps out there, one could equal this that I am not aware of, for less. I do not know. But I bought into Pass Labs for many reasons. One, Nelson Pass knows his stuff. Two, they are made in the USA and it’s heirloom quality. They have a low fail rate and superb customer service. Add to that the Glorious sound and it’s a home run. A pricey one. The Heresy IV’s react very well to changes in equipment and yes, even cables. The III’s not as much as the IV. Thank you.

  13. The Pass Labs Integrated was tied with the McIntosh for my preferred Integrated, but I just couldn’t pull the trigger because of the cost. I spent much less on a very good Class D, but can’t help thinking I went the wrong way, and should just get the Pass Labs and hook them up to a pair of B&W speakers, and be done.

  14. Great Review, I have this amp and it’s all the things you say it is. It is very sensitive to cabling. The best I found for it was the inexpensive but incredible Triode Wire Labs American Speaker cables and Interconnects….they beat out a loom of cables that cost 4x more. Also, if you pick up some ISO Acoustic Orea Indigo Isolation Pucks and place them under the amp it will do wonders by further adding to the 3d soundstage. Glad you were able to do this review and let people know about this integrated…it’s fantastic.

  15. Another amazing review, Steve.

    I’ve looked at that Pass for quite a while. Have a Hegel integrated that I really enjoy, but Pass is always up there when I look at new amps. There’s also the Coda no.8 which I have been trying to find used, but few seem to sell those.

    • Hi Steve,

      Thank you for your detailed reply about the Vinnie Rossi. I know how much you love that integrated. I fully understand the reason why you sold it. I hsve been there too. Btw I fully enjoyed your Pass 25int review.

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