Dedicated lines will make a surprising difference in alleviating noise and increasing dynamics. If your house is like most modern dwellings, it is likely that one 15 amp line services several wall outlets in your listening room (you can test by plugging in a noisy appliance like a hair dryer into the outlets and then shutting down breakers in your service box, to see what wires service which outlets).
If not handy then you will need to hire an electrician to install dedicated lines. Even though you have a stereo amp presently, you may want the electrician to install separate 20 amp lines for amplification of two mono amps to have them available should you upgrade someday - it will be cheaper to do this once and not have to call the electrician back to run another wire along the same route when the upgrade bug bites you. And also a dedicated 15 amp line for your pre-amp and source into a duplex box, with maybe an additional duplex outlet for additional sources like a turntable or computer audio.
If you don't want to do all that, something you may be able to do yourself is install new power outlets. When I installed a dedicated power line for my pre-amp and CD player to take them out of a ten-outlet chain (!), I changed out my stock outlet for a Furutech GTX outlet and found it did improve the sound a surprising amount beyond the initial improvement observed by putting in the dedicated line.
If not handy then you will need to hire an electrician to install dedicated lines. Even though you have a stereo amp presently, you may want the electrician to install separate 20 amp lines for amplification of two mono amps to have them available should you upgrade someday - it will be cheaper to do this once and not have to call the electrician back to run another wire along the same route when the upgrade bug bites you. And also a dedicated 15 amp line for your pre-amp and source into a duplex box, with maybe an additional duplex outlet for additional sources like a turntable or computer audio.
If you don't want to do all that, something you may be able to do yourself is install new power outlets. When I installed a dedicated power line for my pre-amp and CD player to take them out of a ten-outlet chain (!), I changed out my stock outlet for a Furutech GTX outlet and found it did improve the sound a surprising amount beyond the initial improvement observed by putting in the dedicated line.