As Jon Raines pointed out, the Meridian 271 was created to address this problem albeit not nearly as ideally as would be a new Immersive capable M processor with direct HDMI inputs and DACs capable of dealing with all current native formats.

As for a matching high quality Meridian DSP speaker solution for best practice Atmos ceiling installations, you would need to look at the long discontinued DSP33. It has proper reinforced hardpoints on the rear that could be used with the same K&M #24496 heavy duty tilting ceiling mounts I'll be using with the ATC SCM12i Atmos height channels I'm adding.

2ch: Jay's Audio CDT2 Mk3, PS DirectStream Dac, Oracle Delphi VI/SME V/Benz LP-S, Coincident Statement Linestage, Foundation Research V5 Phono, JL Audio CR-1 xover
M-ch: OppoMod 203, Anthem AVM60, 2x 557
2x or 5x ATC SCM20ASL mk2, 4x SCM12i, 4x Seaton Submersive HP, AM2.0 sub EQ
Video: JVC X990, Isco 3L A-lens/sled, 105" motorized 2.37:1 AT screen