No matter how I go there will be compromises.
I took a closer look at possibly moving furniture around and placing the LS6s on the stairwell wall, only out 4 to 5'. It turns out the couch is too long. It's nearly 12' long - a 5 part couch with each section reclinable and the end ones are powered. The chair is a matching powered recliner. We spent a lot on them and the WAF is zero for replacing them.
My pre is a Marantz AV7005 so I do have Audyssey capability.
I'll plan on bass traps in both corners. I'll have to adjust there a little as the A/V-1RS will have to be closer to the rear wall than I'd like.
How far apart should I place the LS6s?
I would not use Audyssey.
I find that EQing, especially in these processors and receivers, are more detrimental then beneficial.
Ethan from real traps, explains it better then I ever could.
http://realtraps.com/art_audyssey.htmIf you have to use that wall, you HAVE to get acoustic traps behind you. Get some GIK Monster traps, some of their stands, and set them up right in front of the window behind you to ear level and above.
Treating the corners is also critical. Also, treat the walls behind the speakers as much as possible with GIK Monster Traps.