@atdavid, the Pass XA30.5, as well as the XA25 which I use, and I believe most or all other Pass XA amps, operate in class A up to and somewhat beyond their specified power ratings. (I say "somewhat beyond" in part because those ratings are specified very conservatively in terms of distortion percentages). But at higher power levels these amps transition to class AB, resulting in much higher power capabilities than are specified, as illustrated by the reference Twoleftears provided above.
To provide an additional example, my XA25 is specified as having capabilities of 25 watts into 8 ohms and 50 watts into 4 ohms. Yet
Stereophile measured 80 and 130 watts per channel into those impedances, respectively, at 1% THD + noise.
Also, the paper by Nelson Pass on
"Leaving Class A" that I referenced earlier in this thread may be of interest.
Best regards,
-- Al