Is the above info outdated ?Whereas typical class D designs, are much more efficient, and engineered to their rated spec... with a switching power supply, and an amp designed that way, you get exactly that - your 100W amp will give you 100W and nothing more - no headroom beyond.
Often rated continuous power and peak power are the same (or very close to) for ClassD desings.
Traditional AB designs often publicise their "peak music power" - sometimes this is snake oil - where they advertise the amps ability to put out big W's for a very very brief time... in an attempt to get the customer to think that this is the amps continuous rating....
But the decent (and reputable) ones, rate their amps at continuous ratings, and then may provide information on peak/headroom specs.
I see the opposite with HYPEX amps all being advertised at the max spec and Yamaha AB's advertised at RMS.
Also, the HYPEX has a comparable margin between its rms & max ratings.
Lets compare two currently available/popular D & AB amps:
Hypex NC252
8Ω - 100rms / 150max
4Ω ------------ 250max
2Ω ------------ 180max
Yamaha A-S801
8Ω - 100rms / 140max
4Ω ------------ 220
2Ω ------------ 290