My room has no parallel walls only the floor and ceiling.
OK, do you have any room measurements yet? How will you apply room correction to your 5.1 setup?
The reason I posted those links above is the panels are portable. With the ASC or Auralex solutions you could have any "walls" (like the Attack Wall") you want.
You talked about acoustics, the reps of these companies help you setup as part of their service.
So, can you post some measurements?