A Question About Power-Noisy

I have had a sibilence issue for a long time and after too many equip/cable swaps im beginning to think its really power related. My conclusion is based on the fact that today i was plugging some stuff into my VH Audio hot box while the system was playing and the grunge, hash sibilence got really nasty as i plugged something in and out of the box. Unfortunately, my front end must be plugged into this box because it is basically built into my wall unit which is in turn built into the wall. Bottom line i cant change this power distributor out because of the furniture blocks access to the duplex.

OK, so im in an apt, and trapped with this power distributor. Any thoughts on possible help to tame some of the hash. Initial thought would be to try another smaller pc plugged into the hot box but the box already has some minor filtering....
keep your ALL your cables away from each other. Don't lay AC across speaker wire on let AC cables get near interconnects. This may help and costs zero dollars.

See if you can audition a Richard Grey Power Company, Chang Lightspeed, PS Audio, Audio Magic Stealth(what I use), Audio Prism or some other actual power purifier with your system. If the "sibilance" is power related, one of those will take care of it.
It's most probably the speakers and room-reflections related.

I have spent a lot of money on these (bogus) cables/filters products and they don't help on the long run.
At first you imagine it is better but then the sibilance is back.

I solved mine with the digital room correction and a few absorbers, I had a peak from 4 to 10khz when checking the measurements.
Thanks all for the response. I have considered this to be a room issue. I do use some asc panels up against the large picture window behind my listening position. It helps...but not im in a nyc apt. and am very limited in space and ability to put up anything on the walls permnantly.

The t issue is something im curious about. For no other reasons then space in my audio cabinet i was considering an audio magic stealth mini. The monarchy audio regenerator seems to be interesting as well, but dont know if i have room height wise on my 6 inch vertical shelf.
forgot to add. Are there any easy to use room correction devices out there to check out. I recall some expensive tact solutions but not anything else
It's not the room.

Electroid, it's the cable proximity? Don't make me laugh. People like you took my money.