It's been discussed to death.

The HD621 is basically a 8 channel HDMI to 4 x Coax breakout box. It also applies FIFO and does upsampling. It's rumored it will also apply apodizing filters too. It may be standard practice that anything new that upsamples will now do apodizing from Meridian.

The Player must do ALL the decoding to PCM over HDMI.

Currently Meridian only supports 6 channels input. But the hand full of 7.1 movies synthesize the side channels anyway (similar to how Meridian does).

- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
HT: G61RSL, 4x5K, 5.5KHC, 2xSC6000, Transporter, HD621, Philips BDP7501 4K, Tivo, 65" LG OLED 4K C6
Computer: Foobar2000, 5K, Mojo, HiFiMan HE1000 V2