how long to break in a power conditioner?

I posted this in misc a day or so ago, but I realized that this might be a better place, so here goes...

I bought a Monster Power HTS 3600 MKII about 3 weeks ago. My question is this: The first two days, the thing sounded unlike anything I'd ever heard (I have a Pass Labs x350, Bel Canto Dac3 and some Dunlavy speakers). Unfortunately, about the 3rd day, things started sounding closed in and the highs lost their air and all kinds of other stuff. the sound has gradually improved, but I want to know two things:

1. how long should one usually expect it to take to break one of these things in, and

2. was the added musicality and so on just a fluke?

The system still sounds better than it does going directly into the wall, which is how I was using it up until this purchase, but I'd sure like to get back to that sound I had at first.

Any suggestions? anyone else using one of these and had a similar experience? Should I just chuck it (sell it here) and get a better one? What I want is to get back to that super clean sound I was getting, and I'd love to just know I'm not insane or delusional!!!

Thanks everyone!

Roland