1st, commit to devoting an hour of your time for the experiment. Listen to three songs that you use as a reference recording and make sure that you are intimately familiar with these recordings. Oh, sit your ass in the listening position for this experiment. Don't go walking around the room during this test or you may not ever know what the results could be. Now, go to your circuit breaker and cut the power to every single circuit in the house. Do this to every one but what your 2-channel rig is plugged into. If your rig is using two separate circuits, unplug every unnecessary component but that which will power 1 source [such as a CDP only], 1 pre or integrated and if you do not have an integrated, 1 amplifier [unless you are bi-amping, then power the 2nd amp up as well]. Basically, make your system the most simplistic 2 channel rig you can make it using the absolute least amount of plugs used as possible.
Now listen to the same three songs in the same listening position and using the same source.
Be advised that you might hear the differences better [if any] at nighttime when the grid demand is low. Feel free to post back on any observations that you may have found, even if you found none at all. Have fun during the experiment and don't forget to reset the clocks after you turn the power back on to everything else in the house. Wouldn't want to be late for work and piss your boss off. Whether that boss is considered your wife/significant other or your actual boss at work.
If you experience a significant change in the reproduction, you might want to consider a dedicated line for your rig. If you experience nothing, move on to other aspects of your rig and enjoy the music.