I have the
Philharmonic True Mini Monitors for surrounds at either end of the couch. They have a plate on the back for wall mounting but they are 7.5" deep. Like most of Dennis' designs, they are a relatively neutral speaker. If you look at the measurements they are quite flat on axis and at 45 degrees roll off gently from 5k - 10k. They won't play low (rated to 70Hz) but for surrounds they work great.