Jaimie - you may know all this. M took HDMI out as bad for sound, before more than 1(G91) or 2 models had it for like a year. They did not abandon HDMI rather made it a 2 box affair for logical audiophile reasons for the 861. The chips in the HD621 decode Dolby TruHD and DTS hidef to PCM and pass to the 861. Dolby truHD is DVDAudio modified a little by Rhonda, ex Meridian at Dolby who did it in the first place. Sony bought the codec for present and future refinement.

Basically M has decided not to put up the licensing fees to go Atmos, rather to push in wall DSPs etc. to the install market and focus on 2 channel. This has all been complicated by The Roon spin-off affecting the ability to move forward as originally planned. They never anticipated a hi Rez digital signal would ever be allowed out a processor unencrypted. MQA has put encryption sauce back in since the technical advantage of MHR vs analog was diminished. Unfortunately MQA is no longer in house so we adapt to them vs them optimizing for Meridian.

James
NC1: 861v8, ID41, 218, 251(to outdoors), DSP8000SEUG, 7200SEC, DSP520 rears, Apple TV, DirecTV, Oppo BD103, QNAP251, Roon
NC2-M7005, Triad Silver Speakers,Acurus Amps

FL1: 861v4, ID40, 218, MS200, DSP8000SEs, DSP7200SEC, DSP5000s, DirecTv, AppleTv, OppoBD103, QNAP469, Roon
FL2: Marantz 7005, 251, M60s,60C,33s, Oppo BDP-93,MS200, Roon