does more power=better quality ?

What an interesting thread, amongst all the angst and outrage, some telling points have been made and I've learnt a lot. The only fair conclusion is that there is'nt one, some of the assumptions are revealing, particularly the one that the more accurate and more "linear" the response the better. A good audiophile attitude, but I am, one afraid I don't subscribe to,I like a system whose sound I enjoy with the music I listen to. Accuracy and linearity can go hang.
It seems to me that "low Powered amps" bring certain advantages to the party that allow them to be driven nearer an amps power limits and into areas of higher distortion. The obvious example here is the "soft clipping" of tube amps, possibly due to there tendency to even order harmonic distortion. I would also argue that a class A Watt and SET watt is not the same as a Class A/B, SS watt and I do'nt think that is contentious. So even if amps are driven into areas of distortion, there are good reasons why this is less of a problem in high quality, low powered amps.
Another point I would take issue with, is that in a given range, a higher powered, more expensive amp will sound better than its lower powered brother, into the same speaker. Given the proviso that the amp is matched to a sufficently sensitive speaker, there are many examples where the lower output amp gives better results. I would suggest here the Pass labs Aleph 3, at 30 watts, the lowest powered and arguably the best sounding of the Aleph range.
To consider speaker choice, a good high sensitivity speaker with benign impedence allows the use of low output amps, I use Living Voice Avatars with an 845 SET, to great effect. That does'nt alter the fact that many of the very best, full range speakers, are power hungry. You can't run Wilson Grand Slamm or BandW 800 Nautilus on a 3 watt 300B SET. That does'nt make the speaker a bad choice.
It's not suprising, I suppose, how many of the threads on this site end up with "it all depends", or "on the one hand X and on the other Y". Few things in life are straightforward and there is'nt one valid approach to system building. The only responses I am dubious about start "well it's obvious" or "the only valid approach is". Frankly if there was only one approach, life would be a bit boring.

It seems to me that "low Powered amps" bring certain advantages to the party that allow them to be driven nearer an amps power limits and into areas of higher distortion

That's a statistical conclusion rather than a fact of life: it's very difficult and copious and much more expensive to produce MANY outstanding watts.
1) Very good amplifying devices (like the 845 tube or the 300, etc) only offer a few db's of gain. More gain increases the complexity manifold... bipolar transistors and Jfets can be good too, but if you want many class A watts, you'll probably end up with mosfets... SO, there's a good choice of devices offering a few excellent watts for less than the price of a new house -- but very few giga watt equivalents (for less than the price of a new house).

2) It makes more practical sense to choose a very sensitive speaker since there is lots of choice out there, and the price levels are comparable to their insensitive brethren.

3) Many tube designs offer their best performance at 1-3W. Many ss devices offfer their best performance level at full power.

When someone says "It makes more practical sense to choose...", what they really are saying is "It makes more practical sense to ME to choose..."

In a perfect audiophile world I actually would agree that high sensitivity speakers are the way to go, but in the real world there are limitations with that approach. For a wide variety of reasons, some logical and some not, there is a limited availability of practical high sensitivity speakers. By practical I mean reasonably full bandwidth (40Hz-20kHz), capable of at least 100dB playback and are not overly large, at least by audiophile standards. Such speakers are available, but it's not as if you can walk into the average hi-end retail store and find one.

For better or for worse the marketplace is dominated with medium sensitivity speakers and 30 to 100 watt amplifiers. Such systems are capable of truly excellent performance. As you move out of the audiophile mainstream you will encounter problems -- availability, cost, limited choices, more critical system matching, less trouble shooting support, etc. For any given person overcoming these "problems" may well be worth the effort, but not all people would agree.

Gregm, "ss devices offer their best performance level at full power". Where does that come from?

Onhwy61:
SS devices: the circuit design.

As to my use of practicality, I do agree. What I should have written is something like, "if *I* were taking the route of outstanding amplification, it would make better financial sense to opt for a few watts and a sensitive speaker.." or s/thing like that.
Thanks!

i guess all those brilliant audio guys who strolled out of m.i.t. and changed the way the world listened to all prerecorded music must have actually been minions of satan. burn all the books and smash all amplification rated over 3 watts. all loudspeakers must adhere to the one driver rule and 'famous blue raincoat' is now sanctioned by the 'church of the para hi-end' to be officially the coolest record ever.