Krell Evo amps correct AC phase

I attended these days a demo of a brand new Primare A32 power amp at friend's place, and what I will remember, among other things (very good amp, btw), was pretty significant effect of switching the phase of power cord's entrance into the wall socket (Europian type of plug). Primare clearly specified in the A32's user guide to be sure that "live" ("hot") wire from the wall should be connected " the left-hand pin of the power
connector, viewed from the back panel".

Any similar experience with Krell Evo amps? Owning a pair of Evo-400e, I have never paid any attention to this issue... Tried to switch the plug position several times today, but results emerged underwhelming, in terms that differences were minor, if any...

Is there, maybe, some factor in Evo amps' construction which diminish effects of correct AC phase? Does, in fact, "correct AC phase" make sense, generally speaking?