The 990's delay is solely a "slow it down" sort of thing - the unit is storing the audio in memory very briefly (in the case of the 990, it is in 1ms increments from 1 to 200) - so you can't speed the audio up. It is done this way because it is a response to video sources whose video processing routines (such as deinterlacing and scaling) take long enough that the video signal is delayed but that do not delay the audio to match. The only way to speed the audio up would be to buffer the video briefly, which would take a lot more memory.