Sometimes my system sounds great, sometimes awful

I've read mixed opinions on conditioners, some say they kill dynamics, probably not all of them.
What I notice the most is how sometimes everything sounds flat and muddy, then sometimes I wonder how everything's sweet and engaging. Maybe I have bi-polar ears.

It seems that many of you agree that power conditioning is a good thing. What is a reasonable power conditioner solution that doesn't break the bank?

Lloydc, you are right. It's 0:45AM and everything's place. Even listening to Spotify free via a bluetooth connection seems to work okay. I also suffer the paranoia about disturbing others, but now that I think of it, maybe the paranoia of being all alone with music blasting at night would be even worse, I could end up looking over my shoulder. Late night listening has also teached me that you can get a lot out of low volumes with a good system. Regarding filters and such I've just realized something, this also happens to me when I play guitar! My acoustic sometimes sounds awful, and sometimes it's wonderful and sings with a light touch. No power outlets or cables involved there, so I vote for the mood, sinus, stress, manic-depressive ears theory.