I've auditioned the INT 60. Smooth as butta'! A very rich, robust sounding amp with a wonderful frequency spectrum. I ended up getting the INT 250 only because I thought I might need the extra power for transient peaks. The first 15 watts in the INT 250 are class A. I'll bet I almost never get into class AB territory, especially in my 27' x 14' listening room. But if I do I'm totally confident the INT 250 will easily handle the peaks. I just hope my ears will, LOL!! As I said, I'm hopelessly in love with my INT 250. But I could be just as happy with the INT 60. It's just a killer sounding amp. I've not had the chance to audition the INT 25. Can't comment on it other than what I've read about it is highly complimentary.
I've auditioned and compared the two models at home. There is a huge difference IMHO.
To resume both have a great definition and quite same sounding in the high but with the INT60 you will have much deeper and more define bass and a wider soundstage.
I've also found the Int25 a little bit "agressive" when you turn up the volume. I've always preferred to keep it under 30.
This could be explained by its limitations in the bass register.
I've kept the INT60 for these reasons.
Gear: AvantGarde Uno Xd, Audiomat Maestro 3 Réf, Esprit Structura loudspeaker cables, D4 XLR ZenWave Audio, Pass Labs INT-60
I have the INT-25 and it is among the best amps I have heard. Integrated of course. It's silky, like velvet. Warm, rich, huge, impactful, real, and has an immensely deep soundstage and just the right amount of details. The 60, which I do not own but have heard is to my ears a tad more aggressive. Either way, beautiful amps. I do not need the power of the 60, so the 25 is magic in my system. I prefer it to the Luxman 590 AXII, Naim Nova and even a tube integrated I have here with EL34's. A true heirloom piece and IMO well worth the asking price. It's not about measurements but how my ears and heart hear the music, and this amp speaks to my heart.
I use the 25 with Klipsch Heresy IV, chord Qutest DAC, Chord Mscaler, and a simple blue sound node 2i (dig out to chord). Nordost Blue Heaven LS cables throughout.
The 25 added bass weight, a silky midrange that is very big sounding and a detailed yet non offensive top end.
The 60 is also a beautiful amp. If I had harder to drive speakers I would have considered a purchase. But even the 25 powers the Q acoustic C300s quite easily and those are 86 or 87 dB.
The room makes the biggest difference, always. With that said, the INT-25 is a much fuller and warmer integrated than the others I’ve had. Naim Nova, Luxman 590axII, and various tube amps, including Prima Luna.
I feel the INT-25 has something very special about it and it’s a perfect match for Klipsch Heritage (modern day newest versions).
@stevehuff Really great comparisons in that review Steve. For people who haven't clicked yet, Steve also has top-quality integrateds from Luxman, Vinnie La Rossie, and Line Magnetic on hand for comparisons. What a privilege to have those in the stable... all beautiful in their own way I'm sure. And really an accomplishment for Nelson to have come out on top...
@bluorion With any Nelson Pass design you should assume it'll get pretty warm. I think his general rule is to keep it around a level where you can keep your hand on the heat sinks for about 5 seconds before being forced to pull away. I've had an XA-25 in my room, and it wasn't crazy hot, but I don't think you'd want to stuff it in a cabinet or anything.
Just an update. I have had many amps in for review over the last few months and the INT-25 is still tops in my book for a few reasons.
I have an INT-250, INT-25, XP-10 and XA 60.8's, a couple of Tube integrated, a Schiit Freya + and Aegir. I have a Yamaha integrated here as well as a Cary 300 SEI.
Running these into my Heresy IV and LaScala AL5's the INT-25 is amazingly sweet. The INT-250 is neck and neck and provides a bit more bass heft but loses a but of that sweetness than the 25 excels at. The separates of XP-10 and XA60.8 are all about smooth and density. I love those as well but at the end of the day when you favor in cost, heat. and cost to run the INT-25 truly wins if you are running speakers that are not so demanding.
For the $$ it's tough to beat in the integrated world. I have become a huge fan of Pass Labs and to date have-not heard any other products or brands that I prefer when it comes to amplification. Nelson Pass IS INDEED a genius.
The Heresy IV and LaScala AL5 are easy to drive speakers with a high sensitivity of 99dB and 105dB respectively, and a nominal impedance of 8 ohms. With these speakers it is not a surprise the Pass Labs INT-25 sounded best in comparison to all other higher spec amps which include the INT-60 and 250. Imagine using flea-powered tube amps with the Klipsch horn speakers. With these high sensitivity horns, other high powered amps will have the potential of sounding aggressive.
Move to more conventional harder to drive speakers with 86 to 88dB and lowish impedance of say 4 to 6 ohms perhaps dropping down to 3 ohms minimum, the tables will likely be turned as the INT-25 takes a back seat while the larger amps which include Luxman L-590AXII sounding better with these select speakers. Think Dynaudio, B&W, Marten etc. as these speakers will have the tendency of sounding flat and lifeless if they don’t get enough current and drive from the amp.
By the way Steve, I bought the Luxman L-590AXII after reading your review of the amp on your page. Your high praise on the amp was spot on as the Luxman sounds very good with my Marten Duke 2. I was actually deciding between Pass Labs INT-60 and Luxman L-590AXII and picked the latter as the opportunity came up. The rest was history.
I’m sure the INT-60 or INT-250 will sound equally good if not better but the Luxman has managed to get me off the merry-go-round of upgrades..
I have an INT60 which is just a fantastic integrated. I decided to get it over the INT25 because of the balanced inputs and also preamp Out and power amp Input which the INT 25 doesn’t have. I plan to play with some tube preamps to see if I prefer it. If so, I may go to separates and maybe even monoblock 60.8 amps. The INT 60 was a good launching point and will likely sell for close to what I bought it for.
Presently I am using my INT 60 with Tannoy Yorkminster’s, Audio Note 3.1 balanced DAC running JPRiver or Tidal Hirez. Also some vinyl..
Sounds good, Markuzz!
I had the Pass INT-30A, and replaced it with the INT-60. Both are very fine: to my ears the 30 was a snootch more musical, and the the 60 a snootch more revealing.
What tipped me to the 60 is that, unlike some of the experiences reported here with the 25A (and many reports other low watt Pass gear), I had trouble driving speakers with the 30, even efficient ones.
I'll be curious to here the results of your comparison! Also keen to hear about comparisons of the 60 and 250.
Initial impressions on the differences between the INT25 and INT60:
First of all, the INT60 is a beast physically. Large, heavy and present. Also the INT60 is deep, and will not fit all audioracks or furniture. The INT25 is a bit more modest. Especially when you switch off the numeric display. This can be done on both, however the INT60 will always display the blue glow of the round fish tank (even when powered off). Although many enjoy this, it is something Nelson could consider for future amplifiers. It would be nice to be able to switch it off, and go 'stealth'.
The connections on the back are a bit more modest as well on the INT25. Obviously the balanced inputs are missing on the INT25, due to the single ended design. But also the speaker terminals are a tad smaller. Nothing to worry about, just an observation. The only ‘complaint’ I have is that the power inlet of the INT25 is close to the handle. Therefore my power cable (with crazy ETI Kryo IEC connector) will slide in the INT25, but on an angle. I enjoy power inlet’s in the centre, it makes cable routing more easy. Why this is different from all other Pass amps on the INT25, is unclear to me.
Both amps sport a timeless beauty, fit & finish are exquisite, and the build quality is top notch. They attract the attention of your friends & family (even kids), and demonstrate your enthusiasm towards high-end audio gear. Both pieces are ‘just’ integrated amps, but you get instant respect from fellow audiophiles, even from ones who still believe the only way ‘is to go separate’. The badass-ness of these Pass amplifiers appeal. To everyone.
Now when it comes to sound, it's obvious they are racehorses from the same stable. They are bred, fed and trained the same way. Their sound signature is surprisingly similar. Thus, what are the differences in sound? Yes…. Well.... the INT60 needs a few more days of playing as she is still almost new at the writing of this subjective ‘review’.
So…. Stay tuned.
Further explorations on the differences between the Pass Labs INT25 and INT60.
Disclaimer: all ‘statements’ written in this post are my subjective findings, based on my system and my room. I ran both amps on my horn loaded loudspeakers, with a fairly high sensitivity of 96dB. Both amps never ran out of breath, heck the needle of the INT60 barely moved at (earthquake) high volume levels. In other words: depending on your loudspeakers, your miles may vary :-)
Another note: I have zero affiliation with Pass Labs.
As mentioned in my previous post, both amps have a surprisingly similar sound signature. Even though this post is aimed at the differences….. let’s start with the similarities.
The 25 and 60 are potential lifelong soulmates to music lovers. They are very capable of reproducing ‘music’, instead of ‘sound’. Both machines bring contradicting sound properties at the same time, such as:
Elegant and exciting.
Coherent and transparent.
Lush and decisive.
These qualities are what many audiophiles crave, but are seldom seen together.
Now…. The differences.
The magical INT25: The advantages of this amplifier is that it it has fewer gain stages. The strength of this simpler design is that it enables to “see” deeply into the recording. The 60 is also good at this, but less than the 25. Also, the 25 sounds slightly more lush and nimble. More playful.
The mighty INT60: Compared to the 25 with a single pair of FET’s, the 60 has banks of smaller transistors. The sound is more rich and resolute compared to the 25. Both amps sound slightly left of neutral, and the 60 has more ‘meat on the bone’. She is also able to take an “ordinary” recording and make it listenable.
Both amps sound incredibly right and will probably satisfy many music-first audiophiles. One of the important factors in this hobby is system matching. It will depend on the other links in your chain as to which amp you prefer. In my system and room, and to my taste, I give the nod to the 60.
Final thoughts on the design of the INT25: I’ve built a few early First Watt designs in the past and I find a resemblance in the INT25. The simple, yet elegant set-up is still intriguing. The dual FET’s connected directly to the loudspeaker without ballast resistors result in low distortion and Class A operation into low impedance and reactive loads. I will not be surprised when Nelson Pass is going full circle to further development on this path for his next (final?) generation of amplifiers. Maybe a similar design with larger heat sinks for dissipation? Bigger, faster power supply? Balanced? A more tuned pre-stage? A recipe for a killer future reference amp.
Been considering the INT-60 to replace my Vinnie Rossi L2i SE once my Devore O96 arrive. This quote from markuzz3000 really grabbed my attention...
As much as I love my high res digital and audiophile vinyl, I still listen to a lot of not so well recorded music that a really revealing system can make unlistenable. In the search for audio nirvana, we often loose sight that the music is half the equation and some great albums aren't recorded as well as we would like.
@aberyclark #1 should be easy enough to test. Find (or make) a quiet track and just plug your source straight into the J2. Then compare with it through the BHK. Or borrow a DAC with variable output and try the same.
As for #2, I haven't heard the J2, but I suspect it would sound quite different from the 25. The J2 and XA25 use different output devices, and a different amplification typology. The J2 has a SET-like distortion profile with 2nd harmonic dominance and the XA25 has a 3rd harmonic dominant profile (I believe this is true of the 60.8 as well). They likely have different damping factors too, so may interact with your speakers differently. Only one way to know which you'd prefer.
@cal3713 one would think if the Pass Labs amps sound great thru Steve’s Klipsch speakers, probably similar with the ZU’s. Thanks for the suggestion. I will run direct dac and see what I hear different.
The Pass Labs INT-25 is a very overpriced amp new. For that price you get an underpowered amp that may have a sweet sound but offers very little else. Slam is especially lacking on this amp, Jay’s Audio Labs’ recent comments on Pass Labs are all correct. I’m very disappointed with my INT-25, can’t believe I paid so much for so little. Very disillusioned with so-called high-end audio. The INT-60 and INT-250 are so completely out of my budget. The stuff is ridiculously expensive.
I have owned the Pass int 60 and it was traded to reno for a int 250. The 60 is a bit lusher in the mids. The 250 is a bit brighter but has more detail and wider soundstage. Im not sure I could say one is better than the other. I feel is just more a matter of taste. Of curse the 250 can drive lower impedance better. Opinions are nice, but you really have to listen.
I have had 2 pass with my Wilson Sophia 2 (89db min 3ohms). Very revealer speaker. Int30A (60w class A at 4ohms), Int60 (15W Class A at 4ohms). I chose the first. It’s a warm sound with necessary detail and information without being fatiguing. I’m surprised how well the Wilson drives, I guess being 4 ohms doubles the power to 60 watts pure A which is brutal, generating the pressure of a live concert. Int60: instead I feel that it has less grip on the bass and generates more fatigue. at mid vol The needle starts to move quite easily because it leaves the class A and the distortion of the class AB is heard.
I would like to try the new Int25 (pure A)
I listened to several Pass Amps (X250 X250.5 X350) and I feel that I like only the pure class A line of them.
If anyone is interested I have nude photos of both of them on my channel. @Mat_audio
It comes down to the load the driven speaker represents.
If you want class A sound one must stay in class A. Though the XA25 or Int25 can produce greater than the stated 25 watts when needed, the amp is no longer biased in class A. Thus some of the 'sweetness' is lost.
I own the XA25 and love it. Drives efficient speakers in a ~15'x12'x8' room.
@kastor77 I would think so unless the room is quite large. Sensitivity specs for speakers are often reported higher than actually measured under real world conditions.
I have driven my Esoteric MG-10s with the XA25 in a 12x15' room with no problem. They are 6ohm nominal, drop below 4 ohm somewhere at lower frequency, and 87-88dB sensitive.
We all have our favorites. I found Pass gear too warm and soft sounding. Also not a fan of the heat and weight of their amps. Clearly, very well engineered and built components, just not for me. After a ton of gear over the years, I landed on Ayre. Love their house sound. Also, like Pass, impeccably designed and made in the USA.
I’ve owned both the xa25 and now the Int60.