Two Phantoms as rear AV channels (bypass Dialog)

[baconbrain]

I would have agreed with your comment regarding inconsistency of audio delay a year or more ago.  I assume you mean that you regularly change the Htpc audio delay to the front speakers to keep them in sync with the Phantom rears.
But since the many software and firmware updates I have found my setup to be very consistent with no need to tweak audio delays.  Perhaps that is because all the speakers are routed by the Dialog and all the relative delays are maintained.  However, I have not found the need to change delays to maintain lip sync so assume that the Dialog is now consistent.
I route four digital stereo signals out from a modded Oppo to three phantoms (left and right, centre and sub, surround left and right) and a Yamaha sound bar (rear left and right).  The Phantoms are all routed via the Dialog which also handles master volume control and the Oppo handles the relative delays and volume difference between all speakers.  The Yamaha has its own audio delay which I have also not needed to change for some time.
Not much help for you I'm afraid.

Interesting setup with the Vanity Board. Sounds like it might be just what I need once it comes out for the 203!