My first thought is that your room has considerable volume and your speakers will need to move some serious air. Wall mounting sounds like an excellent idea, both parentally and sonically, but given the Magnepan reputation for needing watts, I wonder if your planned 320BEE will not be working too close to clipping.
I have had great success with wall-mounted speakers, using the Smarter Speaker Support distributed by May Audio. I've done it to little boxes like the NHT Model One, the PSB Alpha Mini, an Energy 2.1 and a few more, but these were all in small or medium-small rooms. (And with 5-inch woofers at most, they could all use a sub. I've seen wall-mounted subwoofers, and maybe you could consider that.)
In a much larger room, with a high ceiling like yours, an older pair of Mission 761i worked well when driven with a NAD L40 of all things: only 20 watts. These Missions are four times the volume of the others I've mentioned, though, with 8-inch woofers, and are rated 91 dB/w efficient.
Right now I'm working on wall-mounting a pair of AR2ax in a large room. These vintage boxes need power, and I'll be driving them with a 100 w/ch Chinese integrated. They have 10-inch woofers and I expect the lower end to be quite good.
Hope this is useful! Let us know what you wind up doing, if you get the chance.
I have had great success with wall-mounted speakers, using the Smarter Speaker Support distributed by May Audio. I've done it to little boxes like the NHT Model One, the PSB Alpha Mini, an Energy 2.1 and a few more, but these were all in small or medium-small rooms. (And with 5-inch woofers at most, they could all use a sub. I've seen wall-mounted subwoofers, and maybe you could consider that.)
In a much larger room, with a high ceiling like yours, an older pair of Mission 761i worked well when driven with a NAD L40 of all things: only 20 watts. These Missions are four times the volume of the others I've mentioned, though, with 8-inch woofers, and are rated 91 dB/w efficient.
Right now I'm working on wall-mounting a pair of AR2ax in a large room. These vintage boxes need power, and I'll be driving them with a 100 w/ch Chinese integrated. They have 10-inch woofers and I expect the lower end to be quite good.
Hope this is useful! Let us know what you wind up doing, if you get the chance.