I understand the theory , the expensive cables are supposed to filter out more RFI but modern amps and cd players do that already, has anyone here truly heard a difference they can positivly attribute to the cable?
The power supply itself is a different matter. What you want is a clean, filtered and regulated supply that won't sag when the amp hits peaks and transients. You want to start with a high-quality transformer, not some cheapie made by 11 year old slaves in some forbidding backwater. Then, you're going to want it well rectified until any ripple is gone and then nicely regulated. If you want to go the extra mile, put a RFI filter and put DC blocking caps before the transformer.
Assorted snakeoil is not necessary.