With wall mounting, rear vents may end up being in very close proximity to the wall. You are not likely to choke of the bass coming out of the vent, but you will strongly modify the sound of the bass, and it may be overwhelming. Two solutions can be used:

1. If using a subwoofer in a home theater setup, set the xover point to no lower than 80Hz. This will then eliminate frequencies that would normally come from the vent and reduce the problem.
2. If all else fails, sometimes stuffing the rear vent of the speaker will help reduce the amount of bass. An old sock or foam ball can work quite well!
3. Take a look at one of our on-wall speaker solutions