I have a Cisco Virgin HD box that is connected via HDMI to a Sanyo TV and the sound also via Optical cable to external speakers and a subwoofer. I am using a Sonos Zoneplayer 120 as an amp to power Onkyo speakers using an Optical to RCA converter. This works fine for all non-HD TV channels (and also separately using a DVD player) but whenever I turn on a Virgin HD TV channel the sound is replaced by horrible distorted "white noise". Can anyone tell me how this can be resolved? For example Sky Sports 1 works fine but Sky Sports 1 HD has the terrible distortion.