While good mains power cannot be discounted for a variety of reasons, typical power supplies (excluding switchmode, which is the reason for line filters catering to computer users) will more than sufficiently address line-borne noise issues; again, power transformer primary winding inductance and power supply capacitors effectively mitigate noise.

If your mains power is causing audible audio artifacts - which indicates harmonics and line noise far in excess of what is legally permissible in most locales - then address your mains power first.

As opposed to the opinions of some, I believe these discussions - especially cable wars - are healthy; they offer an opportunity for technically-challenged enthusiasts to do research and acquire quantitative analytical skills which are sorely lacking in the audio engineering world - both professional and consumer.

So far as listening evaluations are concerned, I've always been a proponent of double-blind testing, which is a staple of nearly every industry (pharma and food for example), apart from audio that is...

http://seanolive.blogspot.com/2009/0...o-product.html

Also have a look at Floyd Toole and Sean Olive's AES preprint linked in the article above...

I've always been dismissive of typical undisciplined sighted audio evaluations without controls.

Yes, there may be audio phenomena which currently lies outside the realm of present knowledge of psychoacoustics but peer-reviewed research and double-blind testing clearly show that specialist line-level, speaker and power cables are not amongst them.

BobR