Quote Originally Posted by vlad008
really - no one has any opinions on power line conditioning?
Hoo boy and we're off...

A couple of points:
1. Battery powered phono stages get rave reviews in spite of the obvious limitations. I assume it's due to a complete absence of power line noise.
2. A DIY type audiophile on another forum regularly tests new equipment with and without a power line filter. If there is a difference this person adds internal ferrite damping, better bypass caps and fast recovery or soft knee rectifiers. They say that the power line filter will then no longer make a difference.
3. MOV are the most popular surge suppressors, they are cheap and hard to damage. They also generate broad band white noise on sine wave peaks. The transorb type of clamp (zener diode) does not do this but they cost much more, especially the high power varieties.

Noise on AC lines has a very low source impedance, the high frequency parts tend to go right through transformers and show up in the rectified output.

So a power line conditioner may or may not help a given piece of equipment.