+1 since your TV isn’t 4K and it seems you have no surround sound need, this is exactly what I would do - set the Sky device to output stereo PCM and configure the HD621 for stereo.

[edit: when I ran an HD621 this way in the past, with a 2-channel setup, I found that you can config the HD621 with:

- Output Rate x2 (96k)
- MHR

Both set to Yes with no ill-effects. This would be a better way to feed your 7200s, as the HD621 then apodises and uses encryption between it and the DSPs which has the side benefit of reducing jitter. No idea why Meridian marks these to be set as No in their 2-channel config sheet…]

HC: 861v4/ID40/LPS, DSP5000, DSP5000VC, DSP3100, SW1600, HD621, Oppo BDP-105, Sony VPL-HW55ES
2-Channel: Oppo BDP-105, TEAC VRDS-7/Trichord Clock 3/PSU, 551, Quad 303, Harbeth Compact 7ES-3, Kimber cables, Russ Andrews mains and supports.
Previous Meridian: 5000C, 5200SL, 7200.2, 6000, 562V.2, 568.2mm, 800v4, 808.2i, 818v2/v3, 861v8, 502