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.
"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.