Does the VAC Avatar bonk when you drive it hard?

I recommended the Avatar to a friend as an alternative to his CJ PV10/55 combo.He said it was an atractive amp in more way's than one but heard wehn you drive it hard (and occasionally he might) that it sounds lousy after say 11 o'clock.Neither of us can fine the Stereophile review and were wondering if anybody out there might throw some light on this.Thanks.