highfigh is right, take a look of the $17,000 a pair JC1's bench test results:
Parasound Halo JC 1+ monoblock power amplifier Specifications | Stereophile.com
So yes, they may have more 2nd harmonic than 3rd, 5th but at -86 dB, that will be buried and at least masked by your room noise anyway so it won't be heard.
Now take a look of a lowly AVR measured by ASR:
It also has more 2nd harmonics, but a little lower than the JC-1, about -90 dB. Marantz's would have more 3rd harmonics than second, yet more people claimed they sounded "warm".
I hate to call it, but those are internet perpetuated myths, practically BS, not to be trusted as facts.
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Also, as mentioned, many class AB amps do run in class A, but to much lower output level to avoid unnecessary heat with no gain in SQ.
We have compared a Parasound Halo A21 that runs class A up to about 8 W and a Bryston 4 B SST that would run up to 20-25 W class A, though Bryston never advertise that number but would tell you if you ask.
And the result: 0 difference heard!