Suddenly, things are sounding awful...

So I hooked my system back up after about a 6 month absence (though the speakers were seeing constant use in another system for much of that time). 6 months ago, the tonality was fantastic. Things sounded rich and detailed. Now, the system sounds extremely bright (especially on top), very grainy, and much of the detail is gone.

I did indeed change the system's position in the room. But Everything has been repositioned very carefully, and I don't see why there would be any major acoustical problems.

The equipment is as follows:
Silverline SR15 monitors.
Audio Refinement CD Alpha
Audio Aero Prima series 1 integrated
Analysis Plus cabling

The only thing I can think of is that perhaps my NOS tube in the Prima is dying. But could that cause brightness and graininess? Those aren't the symptoms I would normally associate with a failing tube.

Suggestions, comments?

Thanks!