current versus watts

Sound quality has little to do with current (otherwise the tube industry would have died decades ago) and has everything to do with distortion. That is a topic for a different thread.

'Current' is an issue about which there is a lot of mythology. see:

http://www.atma-sphere.com/papers/myth.html

When we are talking 'best', IMO power doubling has nothing to do with it; none of the 'best' amps I have heard have that capability.

I feel that the specs have no meaning if the resulting amp is unlistenable. IOW our ears are more important than the amp is- our ears are the most important aspect of audio. Its important to drop all the preconceived notions about specs, including the ability to double power, if you your goal is for the system to sound like real music. see

http://www.atma-sphere.com/papers/paradigm_paper2.html

for more information

Hi Dob, I agree keeping distortion down is important. Distortion can hide detail. A lot of designers use global negative feedback to reduce distortion though, and this technique often results in subtle enhancement of odd ordered harmonics, specifically the 5th, 7th and 9th, that are used by the human ear to perceive the volume of a sound.

So the resultant sound will sound louder than it really is, in addition it will have brightness. Our ears are so attuned to these harmonics that even 100ths of a percent of distortion of them is audible: harsh, hard, brittle, clinical, bright, chalky, etc are all terms audiophiles use to describe this enhancement.

Thus it is often the case that the use of negative feedback is violating one of the fundamental rules of human hearing perception. So generally an ultra-low distortion figure is often a sign that global negative feedback is being used, and also that the amp may sound like a nice hifi, but will never sound like real music. IOW I am always suspicious when I see super low distortion figures.

Dob, yes, the transient time, propagation delay, plays a huge role in the effectiveness of global loop feedback. I am not sure exactly how fast an amp has to be though; even the fastest amps I have seen seem to have problems when feedback is applied. IMO the amp should be functional with or without it feedback.