Thank you both George and Ronnie for your input. I think you both confirmed my own thoughts that over HDMI it will be the same result sonically going into the HD621 and then the HD621 and 861 will work their magic.
Ronnie thanks for the warning on Pioneer players -- I am aware of it but hopefully they will come up with the firmware upgrade to have DTS-MA on board by the time the new BDP-23 comes out. The Oppo is also a possibility. We will see.

My gear: Trinnov CI, 271, 8000.1(SEs), 7200.1 HC (SE), 320s, 3200s, Seaton F18 subs, MS200 (2nd zone), 218, 210.
Other: JVC RS-4100 projector, Lumagen Pro Radiance, Panamorph DCR anamorphic lens, Stewart G4 130 screen, Kaleidescape Strato K, Rvolution 4K player and Zapitti NAS, Oppo BDP-203,Roon Nucleus