Pass XA200.8 Review - Fun measurements

To the OP's question, I think there is undeniable distortion in the amplifier's output. This appears to be by design. In the review of the 200.8, Pass is quoted: 

"The lesson of the Xs and SIT amplifiers was that a small amount of second harmonic of a particular phase character gives a desirable sonic result. To get that effect, we altered the arrangement of the constant-current sources in the output stage to better duplicate the sound of the Xs output stage. While the .8 amplifiers still have low distortion, they do not suppress second harmonic as much as the .5 series, giving a mostly second-harmonic character at ordinary listening levels and segueing into third harmonic at higher power."

Also: 

"I don't think the audiophile wants technical perfection. He wants to be happy.—Nelson Pass"

Read more at https://www.stereophile.com/content/pass-laboratories-xa2008-monoblock-power-amplifier#EuGPmgvtCD4uc...

Great points about the distortion though. I own a Pass amp and am extremely happy with the euphonic distortion. I personlly appreciate Pass's approach to amplifier design. 

yes, it is, and they say so themselves, but a bit in a disguised way. They built amps for what one hears, not for measurements. If one likes the sound, who cares of measurements?? which even excellent sounding tube amp measures well... none!!
either you buy on sound quality/performance, or on specs/measurements. My Benchmark AHB2 are good amps and measure brilliantly well, but in performance against the Pass, not many will choose the Benchmark!

shadorne,
i have nearly all from Benchmark, all dac models and amps. Used the AHB2 in mono on Tannoy GRF90 through very good tube preamp. Very nice sound, fast and dynamic, which to me are the strong points of these little marvels. Tried the XA160.8 on same: so much better in just about every aspect of sound; especially tones, bass, coherence, soundstage and overall musicality. No comparison. But i still love my Benchmark gear. They are better adapted to other speaker types, and Pass is very well suited to Tannoy in general. Nelson Pass does lots of evaluation on Tannoy, and Desmond Harrington, president of Pass has Tannoy at home!! As much as I think we can say Pass XA are not adapted to the Wilson.

hddg :

I very much care about measurements. That is part of how I enjoy this hobby is learning what measurements mean to perceived sound quality. That doesn’t mean I buy based on . specs. The point of this thread is very much to help illuminate this aspect of our hobby. Whether distortion is a selling point.

I also wonder how much of this is learned or trendy. I’ve lived with Parasound and Class D amps that have much lower distortion figures than Pass. I also loved old CJ tube amps. I simply do not like the Pass sound at all. The point is not that you should agree with me, but rather, I wonder if this is in fact a learned or acquired taste? Does our ear / brain mechanism change according to what we spend time listening to?

And how much of this is driven by reviewers and price? I’ve seen plenty of evidence of this in speaker land. 

Kind of related to this, I really would have liked to have seen what Carver did when he attempted to match the CJ Premiere amps. Did he add more harmonics? 

Best,

Erik

I read the measurements and they are quite respectable and aren't pejorative in substance or assessment.  I'm not sure of the point of this post, other than an axe to grind with the concept of Pass?  These amps are massive, heavy, and there are two of them. Adjusted for inflation, the XA100.8 pair would have been about 6.5K in the mid 80s, back when a Levinson 200W, unbalanced, stereo ML-3 was 5K. A pair of ML-9 amps was 6K which would be about 18-20K today.

Want to spend less? Choose the X60.8.  I have a pair of XA100.8 which replaced the XA60.5 which replaced Classe MA-600 and Luxman M800a, which replaced a pair of Bi-Amped Accuphase A50s, all of which were excellent.