With the new information here - thanks - I can see the way forward for me. VK and Rick confirming the role of the HD621, when to use and not to use, was most helpful.

First:
Trade-in 808.2 for 808.3
Digital SPDIF and optical inputs to 808.3 (eg TV, Bluray, Sat)
HDMI direct to screen
SpeakerLink out to DSP7200s
Now who would have thought that a “CD player” would do so much!
I will not need a HD621

Next:
Sooloos to ID40 in 808.3 for best possible audio from Sooloos

Finally:
Multichannel and therefore 861v6 without an ID40

Confusion to clarity. Nice.