There's almost certainly no such thing, Ross. Unless the power cord is substantially undersized, which is extremely unlikely with a pre-amp, power cords never improve performance. As for the power supply, pre-amps don't draw a lot of current, so it's very likely that if the pre-amp works according to specifications the power supply is as good as it can be. Anyone who tells you a different power supply or a power cord will improve performance is selling you snake oil.
