The 565 does have a digital bypass but that would be of no use since the 818v3 cannot process a DD/DTS signal.

The Sky+HD box has both digital optical and co-axial outputs but they both deliver the same stream type. Setting the box to PCM makes it output stereo PCM (which I believe is broadcast as a separate stream from the DD and not mixed down on board - I don't know how terrestrial TV is broadcast or how TVs do things) for all channels. Setting the box to DD outputs DD 5.1 or DD 2.0 for channels with those streams and stereo PCM for those channels which do not.

I would be interested to hear your results if you do try this out.

In the spirit of Spinaltap, I would like to confirm that I am not involved in the corrupt theft of a global sport.