Short List of Amps I prefer over the Pass Labs XA25 or INT 25

Different strokes...it's all about preferences. I'm a "Passaholic." I love the Pass sound. It's so rich sounding to my ears. Most people feel the same way about their gear. That's OK! It's alright. It really is. Nothing wrong with differing opinions. I happen to also really like Luxman products. But there have been some posts on this forum where the OP didn't care for Luxman. We seem to have difficulty with the concepts of opinion vs fact. I occasionally have had that same problem.

Two years ago I booked a flight and made the trip to my favorite audio dealer and auditioned 7 different integrated amps. They were ALL outstanding and I would have been happy with any of them. However, as you might expect my ears liked some more than others. The audition included products from Pass Labs, NAIM, Moon/Simaudio, VAC (tube amp), Hegel, Luxman, and Gryphon. I ended up purchasing a Pass Labs INT 250. I love it and my ears love it. All the other amps sounded superb. But I can virtually guarantee you there are people that prefer something other than the amps I tried.

Are all people going to like the INT 250 as much as I do? Of course not. Pass Labs has a pretty lengthy list of very happy owners and fans, so they must be doing something right.

You all know all this stuff. We see it daily on the forums. The differing opinions are one of the things that make the forums so much fun. But some people take the differing opinions personally and are actually threatened by opinions different from theirs.

Anyway, nothing new here. I've seen it on music forums too. I guess it's part of the nature of forums. It would make a great study...the psychology of forums. Anyone care to take that one on?

I don't quite have enough experience to be sure that this is the reason, but both the Coincident 300b Frankensteins and the First Watt F4s are dominated by 3rd order harmonics, while the XA25 is dominated by the 2nd (and all three have low levels of higher order harmonics).  My guess is that my ears are sensitive to the balance between the 2nd and 3rd, and prefer amps that are 3rd harmonic dominated. 

About the F4's distortion, Nelson Pass said ".....the distortion is 2nd and 3rd harmonic in character, rising or declining in linear proportion to the output
power." I wish there were actual distortion vs. power measurements done on a stock F4- at least at 8 ohm loads-that showed where most of the harmonic distortion content was during the first 10 watts. Like your Coincident Pure Ref MK2's, mine are 94db, 8 ohm and never drop below 7 ohms, though they only play down to 70Hz.      

 

Pass Labs admittedly and intentionally adds some even order harmonic distortion to all their amp designs. This is commonly known to be perceived by humans as a euphonic overall sound quality similar to tube amps, which many devoted Pass fans and others desire and enjoy.

Be that as it probable is, it’s probably more true of Pass’ First Watt than of his Pass Labs amps. In any case, I believe it’s well established that the FW amps are primarily marketed to those with high efficiency speakers; 93db and above, and not falling much below 8 ohms. And while I can’t swear to it, I think that typical distortion levels from at least some of the FW models driving speakers like those are respectably low. However, I've yet to see much in the way of a full set of independent distortion and other measurements done on most FW amps-certainly not on the F4, which I own and plan to use with my new speakers. The one exception I know of was the Stereophile review of the FW J2, where JA did his usual array of tests. IIRC, the J2 did quite well with 8 ohm loads.