I thought long and hard last night about going riser at bottom of the stairs and back part of room. That was the first scenario I was trying to envision down there. And I really liked that idea. I wouldn't mind the step down to the other side of the basement at all. However, I just can't see how I will be able to put a standard size door (height-wise) in Wall B on top of say a 7" riser. The riser would have to be as tall as my last step on the stairs (which is a standard size step). Remember, slab to joist is 91"-92". If I were to build Wall B on top of a 7" riser, the top of the door opening alone is at 87" and I haven't even accounted for casing/trim above the door yet or losing 1"-1.25" if I double up DW on the ceiling.Why not move the water heater over, and move both doors to the back of the room, and the circulation space to work, as separation from rear surround speakers?
If you do a riser at one step height, then you could basically extend the bottom step to the back wall, and you enter the room at riser height, which also will hide
the hot water overflow discharge line. Now the hot water tank will need to be moved over slightly, to create a bit more space, but you now have a simple hinged
fabric panel hiding the door. The rack could be right outside this door, with a nice short conduit run to the projector, which needn't be short throw. Those bar seats
could now be roller chairs, to easy seating access.
You did mention moving the water line, and an electric hot water tank move shouldn't really wouldn't be that much extra work. (It does sound like you have some construction skills.)
I also think you might be shortchanging yourself on screen size. I also wouldn't drop that front section of room, to 80". You could also play up that entry area as a feature wall, and
have a movie poster lightbox, or a digital one.
The front post could simply be boxed in. You won't be seeing it and I'd doubt it would have any really impact on audio. You do want to absorb the small amount of energy coming off
an AT screen's backside.
Anyways, just tossing ideas at you...
I would not be able to carry a riser thru to the laundry area because there is a sump pump in the corner directly across from the HW heater (or in the case of your latest mock-up above). That area is only about 7 or 8 feet across to give you an idea of scale compared to the theater room. Plus, we are building a closet in there with bi-folds that will close off the HW heater and the sump pump from the laundry area. There is no room for the rack in there either as we are eventually going to put a bathroom next to the laundry area (in fact they are going to rough in some of that in the near future so we can build at a later time).
I also saw your comment about not dropping the ceiling to 80". Just to be clear, the bulkhead/ceiling on what is now proposed to be the front of the room is at 80" now. So, if I were to do some sort of a little stage along the front wall, I'd like only be working with like 71-72" of height on that wall (after stage, layers of plywood and carpet). IYO, would you go bigger than 100"??? Ideally I'd like to leave a MINIMUM of 3-4" above the screen so I have a little play if I go the projector route.
And you are correct about not seeing the newly exposed lally column in the front of the room. Just so I'm clear, I have to build a wall inside the existing wall (even where we planned to kick it out) so I can get that lally to fall in between the existing wall and the new inside wall. But, I am thinking I can use this to my advantage and essentially build a wall inside a wall - great strategy for soundproofing. I measured this evening (and cut a hole in the wall to see exactly where the lally falls) and it looks like I will lose just 7" of depth in the room by building another wall to hide the lally. I just have to be careful because the location of that lally could very well be near the location of the right front in-wall speaker...it's pretty damn close.