Doggitter,
I wasn't confused at all. What I'm trying to say is that the electronics are only a part of the system and no one can just say that the 685s are going to sound good in your system.
I owned the 685s for a little while and found that the 685s are pretty sensitive to placement to get them sounding good. The 685s also like power. I'm not sure that either of your amps are going to give you what you want, especially playing rock.
In my system, the 685s didn't like being on shelves or close to the rear walls. They much preferred being on stands at least a couple of feet from the rear wall on stands.
If I'm understanding you right, you have a surface that is at about shin height that is 7.5" deep that will accommodate a maximum height of 39" and a maximum width of 11".
If I'm reading you right, I think you have two problems. The first is that your speakers are going to be at about knee height without stands, which leads me to the second problem. I don't think that stands are going to fit onto a shelf that is 7" deep. I don't think that that there are many speakers that will accommodate a 7.5" depth, physically. Even if you were to be able to sit speakers there, you aren't going to get much more than sound coming out of them.
Really, I've heard some fairly expensive speakers that sounded spectacular at the audio shop that just plain sounded like cr@p when I tried to put them on shelves.
As for the 685s, they like to be on stands out away from the rear wall. Their sound quality can range from excellent to horrible, depending on placement. The 685s also aren't the most efficient speakers. They like power. According to B&W's website, they have a nominal impedance of 8 ohms, but are also listed as going down to a minimum of 3.7 ohms. They are also over a foot deep, not counting the wiring.
Keep in mind that I've never had either one of these amps, but based on the specs, I'll take a guess and say that the combo won't be ideal. I don't think that either amp will have the muscle to really bring to bottom end under control.
If you have to put the speakers on a 7.5" deep shelf (essentially), perhaps you should look into some speakers designed to be hung from a wall. One brand that comes immediately to mind is System Audio.
I'd also suggest that you try to add a good sub woofer to the budget.