I have not had this problem. Why don't you run the audio AND video thru the 990? Seems like the obvious, easy solution to the problem. Of course it may not be easy, but you know what I mean.
It can't hurt to try it, and see if it fixes the problem.
Good Luck,
Lonster
P.S. If you DO throw it out the window, let me know where you live so I can be there to catch it :-)