I had all of the sound issues listed in above comments plus my house is old with 2 phase, ungrounded circuits. I purchased a fairly inexpensive Panamax conditioner and the previous grounding problems (slight current running on metal faceplates, sounds scary) was eliminated and background RFI noise was eliminated. I did pop for an Amazon upgraded power cord for my amp (about $25) and that seemed to help with some detail nuance.
We are in the process of remodeling and I plan on a major electrical upgrade. I may spend the extra for a dedicated 20 amp circuit for the listening area.