Digepix, I understand that you consider class A better sounding, otherwise you wouldn't care. It should be better sounding if it is designed that way. Class AB has to use more of negative feedback to counteract nonlinear operation of output transistors. This negative feedback improves everything: THD, IMD, Bandwidth, Output impedance etc. but unfortunately can produce Transient Intermodulation (TIM) - basically overshoot of fast changing signals (signal fed back is late because amp introduces delay) that in frequency domain shows as addition of odd order harmonics. Since it can make sound unpleasantly bright designers try to keep amount of negative feedback to minimum. 30dB gain of power amp represent voltage gain of 30 but amplifier will most likely have gain of 300 in class A and 3000 in class AB before feedback that brought gain back to 30 was applied. Class AB needs more feedback (and therefore initial gain) not only to linearize non-linear operation of output transistors but also to reduce "gm doubling" effect. Gm doubling (trans-conductance doubling) is simply gain difference between two (class A) vs one (class AB) transistors operating at given moment.
Since your amp has both - nonlinear region of transistors and gm doubling it has to use more gain and "damage" was already done. This whole issue is very complicated and it was even shown that increasing bias in typical SS amp can actually increase THD distortions (overbias). I'm sure Krell engineers know what they're doing and this amp can sound better than class AB amp but it is not as good as equivalent class A amp at any loudness level.
I understand you need to know what you really got for your money but I would pay more attention to system synergy and overall sound and less to classes of operation, specifications etc. Often amp with poor specifications has wonderful sound.
