I have a Spectral preamp that has an outboard power supply with cheap factory cabling into and out if the the power box and have tried upgrading the cables and there was no audible difference in sound.I have an expensive set up and have upgraded most of the power cables but spending more than $100 to get decent connectors and shielding is useless.The power comes from the plant down the power lines into the house wiring addding a firehose $5000 per cable is ridiculous.The very best audio equipment is not improved by adding 3' of ultra expensive power cable from the wall plug to the input.