does more power=better quality ?

A1126lin, I think your question is rhetorical, at least I hope so. As Gmood1, Nrchy and Thorman already said, quantity and quality have never been the same thing—and I don’t think they will ever be. I would like to bring up a couple of additional issues that are relevant to your inquiry.

Throughout the years, the best sounding solid-state and tube amps in the midrange—with some notable exceptions—tend to be those with low to medium power. This may or may not be a coincidence as high power tends to require pushing the design and the parts to work closer to their limits with unavoidable penalty in the sound.

The other important parameter in selecting the power of an amp—the most important one in my opinion—is your listening preference. If you like small-scale, intimate music, you’ll be very happy with low- to medium-power amp. If you like heavy rock music and large-scale symphonic music with thunderous bass or subterranean organ notes, you’ll never be happy with low- or even medium-power amps no matter how efficient your speakers are.

I run into this dilemma all the time so I have both medium-power tube amp and high-power solid-state amp in my system and use one or the other depending on the kind of music I listen to. But switching amps is a pain in the neck. Bi-amping solves most of the problems though not all but that’s another story for another time.

No, but............

In the case of what some like to call "digital switching amps":

Taking a given module, and operating it at both the lower and upper end of its operating range, most listeners prefer the sound at the upper end of its range. Mainly because it "sounds" like it has more drive.

Since the stored charge in the supply caps, and therefore the amount of energy available on short transients, is the product of the voltage squared times the capacitance, raising the voltage makes a more dramatic effect than raising capacitance.

So, if that is your main consideration in determining sound quality, yes, there is a valid reason why it could be true.

In the case of a Class AB amp, operating at a higher voltage reduces the capacitance in the devices that determine the bandwidth and phase margin of the amp. Both of these could lead to minor improvements in sound. But only up to a point. Beyond that, the changes are negligible, and other factors enter in that make amps harder to build.

thanks for all the inputs.
i should elaborate more on my question.
let say if i use a bookshelf speaker ( revel m20 or bw 805). i get the impresseion from some post that lower / midpower sounds better than the higher power model ( within the same brand ) for example. some have say pass x250 sound better than the x350, or a krell 100 watts sound more sweet( whatever athat means ) than a 600watts krell amp ( again same company and same line product) i was comparing a sony receiver to a levinson amp.
i like to know is it true and why

correction
i mean i was NOT comparing sony to levinson amp

S7horton,

Let's take the comparison of the Classe CA301 at 300 watts
and the Classe CA201 at 200 watts.

If the design of the amps is essentially the same, and Classe
selects components with the same quality; but it just puts
more transistors in the CA301 than it does the CA201; then
yes.

For the same load, the transistors in the CA301 will each
be providing less current than their counterparts in the
CA201. Therefore, because the transistors in the CA201
are putting out more current - they are farther out on
the transistor's response curve. Depending how linear
that curve is - indicates how much less accurate the CA201
will be than the CA301.

If the curve was perfectly linear - then there would be
no difference. But real transistors never have perfectly
linear curves. The CA201's transistors are extending
farther out on the curve than the ones in the CA301,
because the CA201 has fewer transistors to carry the same
load.

The difference may be marginal, if the transistor's
characteric curves are fairly linear; but there is a
difference because the curves for real transistors are
never perfectly linear.

Dr. Gregory Greenman
Physicist