I won't claim that power cables cannot or do not make a difference, but i will say, based on a LOT of comparative listening with some very high end gear, that its a modest difference and not always an improvement over industrial stuff. If they do, they must be filtering out power line hash, and that points to better solutions and bigger problems.
I didn't comment to start an argument--- rather, i am responding to your adjective "modest". If indeed your system is modest, and you are not a magician, then I am certain that you can spend your money more productively elsewhere. Typically DACs and speakers have the biggest faults these days (or, the inverse, make the biggest improvement). Its the weak link in action - find the weakness and upgrade it. (note: my first professional designs were amps and preamps.... so I'm throwing stones at myself....)
One thing I've learned over the years is just how superb a system can be even with home depot wires. Since I design gear, i am constantly swapping in and out pieces that might explode or so something bad at any moment. So i often have rigged wires and boxes in my system to add protection fuses (horrors!) using whatever i can find (lamp cord, 30 year old banana plugs..). And lo and behold, when i get everything else right, it disappears.
Just sayin
G
