Thanks. I think I'm getting myself confused.

When I say eARC, what I mean is the TV/extractor uses its eARC channel to pass uncompressed audio, over HDMI, into the HD621, so that I get the highest quality audio from 4K sources.

e.g. TV eARC -> Marmitek -> HDMI Audio -> HD621 -> G61R

My question really is, do audio return channels on HDMI always pass audio out on that port, even if the TV is on another source?

Meridian G61R, HD621, DSP7200L+R, DSP3300C, DSP3200