Dave Ellis
I agree on speaker cable. I think you are better off spending money on better electronic components, be it polyprop/polystyrene caps, Caddock/Dale resistors, better power supplies (discrete over conventional regulators) or if you have s/s amps, more capacitance in the power supply amd (as you said) better rectifiers such as HEXFREDs
I have always failed to see how 6ft of speaker cable can have any real impact on the signal when using valve amps with output trannies - the amount of copper wire inside one of these is far greater than the average speaker cable, yet people will spend $000s changing speaker cables. Or better still, the signals in most amps travel on very small copper tracks on the PCBs (layers are usually 0.035mm) and the width might be 6-10mm if you are lucky. Of course they work fine, but dare I suggest that thickening these would offer a far greater improvement than changing cables?
In my opinion (for what it's worth), spend your $$$ on better speakers to start with, and then better amps, premps & sources. While I'm on my soapbox, I recently saw an article in a UK HiFi mag recommending a system where the speaker cables and interconnects were the most expensive components...and it wasn't an April fool's joke. Unfortunately some poor suckers probably took his advice...