I got my 606 the other week and am very pleased so far. I just got my new sound card (HT Omega Striker 7.1) for my computer so I can finally get good audio out of it. The receiver got video via HDMI and then I ran an toslink cable to the receiver for audio.
All works well when I play just audio from my computer. However, when I run audio+visualizations (using Winamp) or video with audio, the audio keeps repeatedly dropping out every 5-90 seconds for 3-10 seconds. Curiously, when the video signal was just my desktop background everything was ok.
My solution to this after troubleshooting for a day was to run an RCA to 2-pin S/PDIF cable from the sound card to the video card. (I would have done this in the first place but I didn't realize the video card - GTX280 - had S/PDIF in). Now both the audio and video run through HDMI and the receiver is just fine with it.
Is this normal behavior for a receiver? It acts like it is trying to process two audio signals at once even though there was no output from the HDMI. I tried to turn off the audio from HDMI for that connection but no dice.