Time alignment is a concern. However, I've done some preliminary experimentation using a stereo passive preamp by passing one channel through the analogue inputs of my 861 and the other directly to the poweramp. Suprisingly, there is virtually no latency introduced by the 861 so I'm reasonably confident that any issues can be dealt with using speaker distance setting etc. Now if the film industry will just release some content to give the format a vague chance of success...

Main system - Sources (Kodi-HTPC, Vero 4k, FireTV, Sat) into Trinnov Altitude 32 (8-16) (+Roon), Trinnov Amplitude 8 amp & Vivid Audio (Giya G3, V1.5) and REL Stentor III speakers. Others: F80 + Raspberry Pi and other Pi systems.