Like most people in their late 60's, I do have some high frequency hearing loss (not extreme) and some tinnitus, again not extreme. I can still tell what sounds good and what doesn't. Electrical could certainly be an issue. We always make sure that nothing is running when we listen. Like last night, no washer/dryer, no A/C, no tv, no dishwasher etc. The only thing running was the refrigerator and a freezer. Last night they system sounded pretty damn good, unlike a few nights ago when I felt is sucked. Electrical is suspect when that happens, but it is also affected by mood and which bottle of wine we opened, the last being more important than most realize
Last night it was easy to hear the that the room was an issue, but I still think that the amp/speaker combo is the weak point, as many have suggested.