Acoustic Treatment for a Motif inside an AV Cabinet?

This past week I added a Motif as my center channel. It's sitting inside the top center cabinet space of a BDI Avion 8929 AV stand, which is essentially enclosed on all sides except for the front (there's a small round hole in the back for routing the cables). I have it resting on its enclosed rubber feet, with the feet turned around so as to provide a slight lift for the front of the Motif, thereby aiming it more directly at the main listening position. I really don't want to move this speaker anywhere else. If it goes on top of the cabinet, I'll have to raise the TV too high; mounting it above the TV would seem to make its sound come from way too high (it's a big 70" TV), and on the floor, too low.

I checked, and the little blue light on the back is on, indicating it's plugged in correctly. And while dialogue definitely seems clearer & punchier, I think the cabinet-all-around enclosure is causing acoustic issues. It seems quite boomy & cabinet-enclosed; I imagine that has more to do with the woofers in the Motif rather than the electrostatic panel, since that panel has built-in acoustic treatment inside the Motif, and since it fires so straight-on directionally, I don't think the midrange and tweeter are bouncing around their waves inside the cabinet. I have yet to try flipping the Motif's switch for "on-wall" placement, although I don't think that applies to the woofers, and besides, the manual reports that that setting is for when the posterior wall is 4 inches or less away (and the BDI is deep enough to actually have that be more like a foot away).

Are acoustic treatments for the cabinet space in order, and if so, should they cover all four walls (including underneath the Motif)? What brands and product/model numbers can you recommend?

Or perhaps, should I intentionally hamstring the Motif, directing the AVR to crossover to the subwoofer at all frequencies below 200Hz?

At least start with behind the Motif and see how it sounds. Just play with it until you like the way it sounds. There is no hard rules for this treatment.

In this case, I'd recommend stuffing the cavity behind and the spaces around the unit with some absorbent materials.

For the space behind it, some OwensCorning 703 insulation cut up into blocks that fill the space (and subsequently wrapped in some porous cloth like muslin) would do the job. Please see this thread for details on how we did this for some treatments in my setup: http://www.martinloganowners.com/forum/showthread.php?6832-DIY-Room-treatment-panels

The space between the edges of the Motif and the cabinet should be closed off or stuffed as well.

Make sure the Motif woofers are flush with the edge of the BDI cabinet. This means the ESL will stick out a bit, but that's fine.

Do set the switch for 'on wall' as that will damp the low-frequency resonance you noted.

In the processor, set the crossover for the center to 100Hz or even 120Hz. The Motif is good speaker, but can't really deliver below that range at high volumes.

Thank you JonFo! I'll work on this soon.