Sorry to hear you're not happy with the 990. If it sounds as bad as you say, I'm wondering if maybe there's some flaw with your unit.
How are you connecting you audio source to the 990? Analogue or digital? CD's sounds great on mine...stereo, upsampled or bypass. My previous pre/pro was an Adcom GTP 600, with which I used the analogue-out from a CD player and it functined purely as a preamp. Going digital out from my player to my 990, CD's sound better.
Of course, movie sound tracks are a world of difference, as my Adcom was pre-Dolby Digital (DPL only). DVD-A via the 7.1 direct input sounds great also. But I have no experience with your HK, so I won't attempt to tell you that what you're hearing isn't valid. It does however make me think there may be some malfunction with your unit or setup if it sounds that bad.