VK,
I don't see why you think with a Darblet that it would be better to put the HD621 before the Radiance. What's the logic?

I currently have the following chain: Radiance, HD621, Darblet, projector. I don't like it because, as i mentioned, it limits mixing and matching audio and video outputs which is something I like to do sometimes, and I've had some apparent handshaking issues with it from time to time.

MD600(2x2TB); iPad Pro
LR. 818v3, 8000SE
HT. 861v8+ID41,HD621; BW 2x802D,HTM1D,4x804S;SVS sub; Mac 5 MC501s; RGP 600Pro, JVC X950; Radiance Pro; Oppo 203
FR. G65, DSP3200-3300 DSW, HD621; Mac MC152; Oppo 103, PDP TCP65VT60, Radiance 2124; RGP1200C
4. G65, DSP3200-3300,HD621; OPPO 83, Radiance XE PDP
5. 818v3; Prime HP Amp; HD800