Put the Hi Fi on it's own dedicated circut. Better still, put the amp on it's own circut and the rest of the system on another-all on the same side of the Buss. For the amp, bump the wire size (such as #10 for a 20 amp circut that requires #12, or #10 if it's a long run the the breaker box). I ran 4 lines when I had the house rewired-one for each amp, one for the pre-amp and sources and one for junk (lights, etc)
And cleaning the interconnect connections is sometimes the only real difference we hear when comparing cables. The old ones never sound as good, because the connection is improved just by the cable swapping process, and we think it's the cables that are better. Maybe this will start a cable argument.
Try listening with the speakers positioned so that the tweeters are slightly above ear level and limit the stuff between them, or pull them forward, if the decorater permits.