That’s a clever idea. Can use the avr amp for heights or sides and use the side preout to feed the subs. Will the avr send the same signal through the speaker outputs and the preamp simultaneously?

LFR1100
VP180HP
EP600
M3 In Ceiling x 4
M5OW
M2 - Atmos rears
ADA1500.5
M3 Outdoor Speakers
ADA 1000.8