Does the power of an amplifier really matter?

As the owner/operator of Magnepanar speakers, I have learned a thing or two about amp power. I have used various amps from 100 to 600 watts/channel (4 ohms) and for every step of increased power the sound quality has improved. This has little to do with how loud the speakers play: the 60 watt amp makes plenty of volume. I don't think that it is the power per se, but rather some other characteristic of an amp which just goes along with the ability to deliver a lot of power.

To Pabelson--WOW, a highly intelligent and thoughtful response. I was thinking along the same lines but you said it first and VERY well.

To Elevick--if your '...around 89db' is intended to address a sort-of-average speaker's sensitivity, don't forget that those sensitivity measurements are done at 1 meter. At 2 meters, that SPL is down 6dB (I BELIEVE; someone pls correct me if that's wrong)...which, of course, reinforces your point about power requirements.

Overall, IMO the 2 most-important determinants of power requirements are speaker sensitivity and desired listening levels. There is maybe 10 deciBels difference in typical sensitivities in popular speakers*, and there's probably more like 20dB difference in typical average listening levels. Combined, that's a 30dB difference which is HUGE.

Eldartford is correct IMO--'sufficient' power gives you a sense of ease, of effortlessness, in playing dynamic music.

* I'm NOT including the rare examples of those speakers in the high 90s and 100s. If I did, that difference might be 20 or more deciBels!
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All of these replies are excellent, and I thank you all for sharing your knowledge. It appears to me that--yes, more power can give you more dynamic headroom; a sense of ease during a John Coltrane solo hitting the highest octaves at high volumes--or Paul chambers hitting the lowest octaves in terms of articulation of tight bass--but, there are probably more important attributes of the amplifier that relate to delivery of that power, and a clean delivery results in impoved micro- and macro-dynamics. So a 100W amp can be much more articulate, dynamic, and have better imaging ability than a 200W amp. The point is that one should not make a decision based on amp power but on musical presentation--which applies to all audio equipment. I just wish I could get a handle on that nebulous amp attribute that allows a 100W amp to shine over a 200W amp, unless that ability relates to a clean power output alone.

Number1, yours is a dilemma common to many of us.

There are no easy answers in spite of what the measurists would have you believe. The ability to maintain voltage in the face of low impedances...IOW the ability to deliver high current...probably is one factor, and the amp's sound at and beyond clipping probably is another.

Amplifier power is just a beginning, and probably not a very good one.
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I just wish I could get a handle on that nebulous amp attribute that allows a 100W amp to shine over a 200W amp

Or, vice-versa of course. Very robust power supply /rectification, matched output devices, carefully chosen components, application of feedback, etc, etc. So many things that are NOT visible to the naked eye...

BTW, regarding spl's, in the near field, ribbons lose about 3db per doubling of distance vs 6db for cones. A difference of 20db spl b/ween sound 1 and sound 2 means 2 is ten times louder than one. To achieve an extra 20 db difference you need an extra 100W of electrical energy. Accordingly, 250W should achieve ~24db. If you want 40db headroom (ie 100 times louder) you need 10.000W. Classical music often has 30db differences. Under normal conditions, that would require 1000W over the reference low passage.
Depressing isn't it:)
Fortunately, we usually listen at low spls and consume milliwatts of our amp's power, so there is headroom enough even with a 50-100W amp -- or less -- for the forte.