Hello,
Yes to all. However, the good news is that I've just solved the puzzle, and now the DSP5Ks are singing sweetly through the Node.
I'd switched the cable between inputs 1 and 2 on the back of the speakers numerous times yesterday, but tried once more, and voilà it now works on input 1, but not on 2. Not sure why, but nevermind.

I appreciate your interest, thanks for your suggestions.

DSP5000 (96/24), Bluesound Node 2