The 990 (and all surround processors) has to determine whether the incoming signal is PCM, Dolby Digital, or DTS before applying the correct decoding. An incorrect guess would lead to unpleasant sounding gibberish. Therefore, the first moment that the digital signal is present the processor must mute itself to avoid such nastiness and decide what audio format it's dealing with. Older stereo DAC's knew exactly what they were going to get (PCM, and 16bit 44.1kHz when dealing with CD's), so they could start working as soon as they had a signal. The trick is to get the processor to make the decision as quickly as possible and to set the delay as short as possible without making it shorter than the signal acquisition time. The 950 was always a bit sluggish at this, with the most noticeable delays being associated with watching satellite or digital cable because the source itself had an audio delay of one or two seconds before even providing a digital signal for the processor to lock on to.