what could have happened?

Plato's suggestion is a good one. If this just came about all of a sudden and haven't changed any components recently, this is a sign of AC related problems. It is possible that there was an increase in noise / interference / RFI on the line. In my experience, this type of situation manifests itself in just the way that you've described i.e. a reduction in warmth and liquidity with a more harsh, brittle sound. A lack of air, separation and black background are also further evidence of this. Either way, if can diagnose and correct this problem, please post your findings and what you did to fix it. I'm sure that others may be curious and you may help them to recognize a problem that their system is also suffering from. Sean
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thanks guys. i was looking at ps-audio upc-200 or the powervar abc or the blue circle hum buster(though i don't think that would condition the line)coupled with dakiom stabilizers. any comments?

I've had good results with the PS Audio UPC-200. If you can find one used it might be worth a try.

Good luck and let us know how it works out for you.

I use two different Powervars, the ABC 1200 for HT and the ABC 600 for analog. They seem to work fine and were considerably less than many name brands. I also have Audio Prism "Quiet lines" on each circuit. There are a number of quality conditioners around (if I had the money, I'd opt for Blue Circle).

You may want to check all other outlets in house (including garage).