There are no special power amp requirements if you happen to have a tube preamp.
My Rotel RA-06 (70W@8) and Onkyo CR-L5 (50W@4) fill the room with ease.
If what you have goes loud enough, and there are no problems/defects, a different and/or more powerful amplifier won't make a difference.
If there is a "weakness", it's usually noise (hum, hiss, or whine in the background). All active analog electronics generate SOME noise and sometimes it's audible. And of course, with more efficient speakers you are more likely to hear the noise. Unfortunately, there is more than one way to measure noise so you can't reliably compare specs. You need apples-to-apples measurements like you'll find on the reviews here.
I measured the power usage of the Rotel amp once.. idle 20W, at listening level 23W.
That doesn't tell you much for two reasons....
Music and other program material is dynamic, which means the peaks are higher than the average. The amplifier might be hitting 50W on the peaks but only averaging 5W.
Of course, that 5W average has to come from the wall power. All we can be sure of is that the
average to your speakers can't be more than 23W.
It's the peaks that are limited by clipping (distortion).
The volume dial was at about 5-10%. These >100W amps confuse me, what are they for?
The dial doesn't tell you a whole lot either because we don't know how much voltage you're getting from your preamp, different sources are "hotter" than others, some songs are louder than others, we don't know the gain of the amplifier, and volume knobs aren't calibrated.
Generally, we want enough overall signal and gain that we can get full power out of the amplifier (if/when we want it) and that typically happens at less than 100% volume setting of the knob. Usually there is enough gain to over-drive the amplifier into distortion. We don't want to do that, but we want the ability to get full power with a variety of variables.
You typically don't need 100W for "home listening", but power requirements are exponential. Double the power is only 3dB louder and +6dB requires 4 times the power, etc. +3dB is "noticeable louder" but it's not a huge difference.
And, these days it's not expensive to build a 100W (or more) amplifier, especially with class-D, and it's a selling point!
