What's Going On?? Sound changes every night

O.K., this is what I'm experiencing: Some nights my system is superb and I just get sucked in and have to force myself to stop. This will be for 2-3 night and then all of a sudden, the next night or three, the music looses life and I can't get involved. The sound looses high end sparkle and extension. Things sound closed in a bit and percussions instruments that the night before were right in front of me are now fake with a closed in and shelved down presentation. Cymbals no longer sound like wood sticks on bronze but as if someone threw a blanket btw me and them.

Is this a power conditioning problem? I use a hospital grade outlet but not a dedicated circuit and no power conditioners. Or could it be my DAC which is a Perp Tech w/ Level 2 WrightMods and cryo treament. When the system works right I couldn't be happier but it seems something weird is going on every few days or so. Could it possibly be coming from the local power company and I need some sort of powerful line conditioner?

System:

Merlin TSM-MX speakers
REL Strata III subwoofer
Air Tight ATM300 stereo amp
Joule-Electra LA150 pre-amp
WrightModded Perp Tech DAC
CEC transport or Marantz SE 5 disc changer as transport
Cardas Golden Reference interconnects
TG Audio speaker cables