Can the 4520, using it's Zone 4 HDMI/matrix ability and/or somehow using Instaprevue, finally allow one to "Watch" one HDMI Source while "Listening" to another, like we could all do for literally decades before HDMI?

Also, it's Awesome to hear about Gapless FLAC since the OPPO 103/105 players don't even do that!!!
I am curious (Still have a 5805CI and wanting to upgrade) if the 4520 can accept, not only through HDMI but also through NET/USB, Multi Channel FLAC's and play those? Does it decode/play those or would I have to somehow convert Multi-Channel FLAC's to PCM and send through HDMI? If the latter, then how does one do this?
Also, I know this may be a bit shallow and pedantic, but coming from the 5805CI (and paying over $6000 for it when new) I was a bit appalled when I went to Best Buy and saw the 4311 used Plastic with a Plastic Volume knob, and also had a thin (and what appeared to be easily broken) flip down door that "clicked" in place.
Can someone confirm whether the 4520 has an Aluminum (pretty standard look/feel to ALL volume knobs on ALL makes/models of AVR's up until last year's Denon Models as far as I'm aware) volume knob and whether or not the door "clicks" to open/close (on the 4311 you would push in to lock and unlock which would click/unclick to secure or release the door) or whether it's like past high end models where the door feels heavy/smooth (and also not plastic) and smoothly glides down and back into place?
I don't feel like I conveyed my last few questions very well. If nobody knows what I mean, maybe JD can help me explain a bit better.

I sure hope to get one of these guys soon and will absolutely be doing comparisons with the 5805CI (with plenty of objective measurements along with subjective impressions) in my dedicated 20x26.5' highly treated (properly and completely, not "overly") and accurate room.
This is the first AVR I've been truly excited about since the 5805CI and finally feel it may be time for an upgrade, that will actually "feel" like an upgrade!
Also, I am excited to see the return to the (IMHO) much better/well regarded Burr Brown DAC's but can anyone confirm the actual Model # of the DAC's used and how many/in what configuration they're used?
Thanks,
--J