I know it's not this simple, but, originally you said you you were using your PC with an optical connection. Later you said you set your PC to output analog signals. You did change cables (from the PC to the 990) and changed the 990 to the correct input, right? Probably way off bass (base, heh) but just throwing it out there.
_________________________
Outlaw Audio 990
Outlaw Audio 7700
OPPO BDP-83SE
Playstaion 3
Panamax M5400-PM
Sony VPL-VW60
Stewart110" FireHawk G3
North Creek Music Systems CM-7's
Dayton Titanic 15" MKIII subs (2)