So there's a second support post at the common bath room and utility/laundry room then? Which means no wiggle room to rebuild that
I can't help but think your original layout is the best layout, and that maybe a set of surround sound headphones might be the soundproofing answer
10x12' is seriously small. And that's a fair amount of work and expense for something so small. I was looking at trying to expand the room's footprint,
in order to keep seating off wall boundaries and the surround speakers.
You could go a little longer, and wider, and take the hallway, and simply do symmetrical soffits down the sides of the room. The screen could stay at the
outside wall, it is currently on. The theater would be a "hallway" for the bedroom/bath room, but that also gets you a wider and longer space. I'm not really
a fan of using a theater as a passageway, but that does allow for a boost in room length, width, and volume. And that gets the seating off the walls, and further
away from the surround speakers.
The bedroom door could even be hidden if you did fabric panelled side walls, and the door could be worked into the frames.
The av rack could use some of the leftover closet depth, if you went small and vertical along the lines of a Middle Atlantic Slim5 rack, as a small footprint
rack, or something custom built along the MA Slim5's compact dimensions. Or the av rack could go into that small storage bump out and be completely
out of the theater.
That would remove noise, and electronic display pollution, from the theater.