Amp's nominal power rating - any use?


I just paired a couple of Coincident Frankentein monos with my SF Guarneri Homage. The sound is great (fat, rich, dynamic, transparent) and sounds well with any type of music (opera, rock, electronic...). These are 8W monoblocks and sound like with more power or at least the same as my previous fabulous pass aleph 3 (30W class A SS). Of course it depends if tubes not tubes, class A or not, speaker sensitivity, impedance load, room dimensions etc, but what i see is that it's not a relevant criteria at all on its own. Maybe there should be some transformation formula to take into account some of these factors to get some Apparent or Perceived Power, but maybe it would be hard to take into account all factors. Any ideas, opinions, on this?
dongiovanni
High-end amps almost always achieve their claimed wattage ratings, but there are amps and then there are amps, and in this regard, what Charles1Dad wrote is true: an amp with massive power supplies (and if it's a tube amp, one that also has the highest quality output transformers) will sound considerably more powerful than most amps of the same wattage rating. Very few amps fit this profile, however (and the ones that do are very expensive), so you're basically stuck with wattage ratings.
Irvrobinson - let me explain. Average music power delivered to speakers is very low - just a few percent of peak power. It is because music on average doesn't go more than half of the loudness and that means 1/10 of the power. In addition music has gaps. Amplifier's max continuous rms power is completely irrelevant. What is important is peak power that amp can deliver.

Imagine two amps:

1. 10W rms, 100W peak
2. 100W rms, 100W peak

In my opinion they will have exactly the same max loudness with music signal.
Amps are rated into resistive loads which says next to nothing about how they do into a reactive real world speaker.

I would propose that amps be rated into 8 and 4 ohm resistors....
Than at the same 2 impedances into +-45 degree reactive loads.

The resultant chart would be a very visual indicator of how the amp does into real loads.

That's the way .....at least on paper to see what an amp can be expected to do.
Magfan,
Your suggestion for measuring speaker output is very much spot on, I wish this would become an industry standard procedure. The current method is of so little real world value in trying to determine an amp`s potential match with a given speaker.