06-21-12: Unsound
Al, Perhaps erroneously, I would have assumed that "all else being equal" extra power would have provided the muscle to reject external noise from seeping in?
Hi Unsound,
No, I don't see it that way. Higher amplifier power will loosely correlate with higher amplifier gain, since amplifiers tend to be designed such they they will be driven to their maximum power capability, whatever that may be, when their input voltage is in the same general area (commonly, although of course not always, in the general area of 1 to 1.5 volts, for unbalanced inputs).
So as I indicated, any noise that is generated or introduced downstream of the volume control will, more often than not, be amplified by a greater amount if the amplifier is higher powered. (Noise originating upstream of the volume control will normally be unaffected by that gain difference, because the volume control setting will be turned up or down to compensate for the gain difference, affecting the signal and noise that originates upstream equally).
Best regards,
-- Al