Blimey, its like a new language to learn. Thanks all for the fantastic information. I've now got a clear idea of what I need to start and what to get built into my walls. And also the next step to improve the AV side.

One more question ... if I'm going with a legacy processor sans HD621 then I'm limited to 5.1. The cost to put in an extra two speakers with wires, etc, could be spent elsewhere and won't be in use for a while. For those that now have 7.1 sound would you say that is a big upgrade on 5.1 sound?

568.2mm, HD621, DSP6000s, DSP5000C, MS600, Roon