Batman: That sub in that room ain't gonna add or subtract from clarity! For sub clarity OP needs acoustic treatment to room with some renovations not to mention a sub upgrade or two. Stick it in the corner.
I call bollox on this!
OP can always try it out - if there’s even space there - and see what he thinks.
Yep, why not try a range of locations for the sub? If you’ve got the cable it’s not like it’ll cost you anything but time. As I mentioned, our sub sits right next to the viewing couch, and that works fine (and better than in the corner!), so sure try it out on the back wall...