I don't think the regulation is a requirment, anymore. In any case, the test protocol was always questionable, from a 'real world' standpoint. Prior to its adoption, David Hafler (among others) was a big critic. The original idea was to stop manufacturers from using idiotic, made up power ratings claiming huge numbers that had absolutely no relationship to the actual amplifier's capability.
FWIW, I have a David Hafler/Ed Laurent kit, a tube design from the late '50s. Modern up to date parts. Dyna rated them (EL34 mono amps) at about 40 watts. From an FTC standpoint it would probably be a 15-20 watt amp. But it sounds as powerful as my 100 watt/channel Yamaha SS, in real life and on real music. The FTC rule was ridiculous for tubes. Why would you want to stress tubes ala FTC protocol? What is that supposed to tell you?
Of course neither the Dyna nor the Yamaha sounds nearly as good or as powerful as my AHB2. I wouldn't pay much attention to the FTC protocol. Again, it was just an ad hoc thing that was made up to control out of control advertising claims, not to get to the bottom of what constitutes good amp design.
PS: from a quick search it appears that the original rule is not in effect, but has been revised. It now includes active speakers, or subwoofers. I don't know how it applies to multi channel AV type amps. I'm all for accountability in advertising. It's just that the FTC rule has to be seen within the context of advertising, and not whether an amp that passes the test is necessarily better than one that won't.
