Thanks for the responses, Chaps.

Vince, it is as I thought. Need outboard DSP.

Albert, don't have an 861, only G91A. Would like to EQ the upper mid/treble regions, not just below 250 Hz.

Syles, I was hoping to avoid an outboard DSP box, even though I have owned a few. I don't see why the separate comms link would be affected by a DSP box in line with the SPDIF feed to the speaker. What do you think?

KTMsteve, I don't run Roon (or JRiver), and don't expect to in the near future. FWIW, none of my gear is Roon compatible.