We are often faced with less-than-ideal placement issues, especially for surround speakers. Ideally, you would like to see rear-ported surrounds placed around 18 - 24" from the rear wall. But more often than not, this is not possible.
Many of our customers end up mounting surrounds on the rear wall. We (and they) have found this to be a very workable wall mount for that purpose.
http://www.btech-usa.com/bt77.htmlWe have a pair wall-mounted with this bracket in our shop. This pair has rear-firing ports and they sound quite good even though they are closer to the wall than ideal. Another option is to move the port. But bottom ports are not possible with this bracked and we always try and avoid front-firing ports. So placing the ports on the top of the speakers is an option provided they are not too close to the ceiling.
In ArthurDent's case, he was placing them on a bookshelf and I assumed they would be too close to the rear wall. So we top-ported those speakers as well. It seemed like the best option considering the application.
- Jim