In double-blind controlled tests people cannot tell any difference in AC power cables. That has been tested many times.

However if it sounds better to you, then I say go for it.

There are many things we do which make no measurable performance difference but make us feel better. Some people swear their cars run better after cleaning out the interior or changing the oil. How much faster does chrome trim make your car?

If changing your power cable or putting stabilizing pads under your amplifier improves the sound (to you), then don't worry about it and enjoy.

Just keep track of the money you're spending and always compare that to alternatives, such as buying more discs, upgrading some other component, etc.