abacus said:
Nothing to do with the loudness (To double the volume you need to have 10 times the power anyway) as most of the time you are only using a few watts of power, but when the dynamics come along (Which can be really big swings) if the power supply is not up to it, the sound falls flat. (Dynamic compression)
A good amp will sound effortless no matter what the music or speakers used, whereas a lesser amp will sound forced. (It can go loud but doesn’t have the dynamic capability to sound effortless)
Bill
Absolutely!
A figure that's useful to look out for is comparing the watts per channel at 8ohms with the wpc at 4ohms. If the power rating is on its way to double at 4ohms, then the amp will better be able to cope with the typical dynamic shifts actually experienced in movies and music rather than playing test tones at 1khz, which is something many users don't sit around doing!! Unfortunately many manufacturers don't quote comparative ratings at 8 & 4 ohms.
And it's worth mentioning that the benefits of an amp that's good at handling dynamic power is just as beneficial at lower volumes. It has nothing to do with how loud you want it played, which I'm sure BB is already aware of bearing in mind the posts above.
Interesting case in point: my old Pioneer VSX-2021 was rated at 150wpc (which may have been a little ambitious in reality I know). My Anthem MRX710 is rated at 120wpc, and yet the Anthem is far better at dealing with dynamic shifts in music and has far better bass grip and timing.
So as far as in-use quality is concerned, I can certainly advocate Anthem. The tonal balance is very neutral: it has decent bite and excitement but the treble is less grainy and it's sweeter than the Pioneer, albeit never dull. The Anthem's downside is its UK price hike the last couple of years.
Another topic: I heard on some video that when using power amps off an AVR's pre-outs, that the pre-amp can sometimes limit the dynamic power to what would have been possible if it was using its own internal amps. Not sure how universal or true that is?