Spent a few hours listening and tweaking...

Speakers are DSP7200.1 for left and right. The 565z3 feeds a digital co-axial input on the 818v3. Pre-sets are Digital for DD and Direct for PCM. Lip-sync is set to 0µs in both the Sky+HD box and the 818v3.

Caveat - my comparison use-cases are swapping from DD to PCM on the Sky+HD box rather than swapping to a PCM stream input direct to the 818v3.

The DD sound quality seemed better (actually really good) through the 565 with bass being deeper and punchier and musical soundtracks being more separated. I do however remember that when I put the 565 into my 5 channel system (after blowing up a G68) the bass was stronger.

The big problem is lip-sync. DD 5.1 and 2.0 soundtracks (via Sky+HD) are fine but PCM channels are way behind the picture. This suggests that whatever DSP (Trifield, etc.) processing is applied to PCM streams is also applied to the Direct pre-set for PCM streams. And it suggests that no processing is applied to the Digital pre-set for DD 5.1 streams and the Direct pre-set for DD 2.0 streams. I have not checked the speaker distances but assume that they would affect PCM and DD streams equally.

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