D subs can be finicky at times. I have found the best results with wiring up speaker connections one at a time power cycling with the remote after each subsequent connection.
Have you tried going with your original configuration and daisy chaining from sub to sub with the reverb being last on the chain and power cycling? Currently running four d2500 and two D1500.

M2.0>ROON: C15/DSP6K
C2.2>ROON: ALLO DIGIONE/DSP5K+D2500x2
W2.2>ROON: C10/DSP33+D2500
R2.0>ROON R: MiniDSP SHD>SCHIIT Freya+(Forkbeard)>3eAudio A7 Mono>>>Apogee Scintilla

Projects. ROON streamer with serial RS232 volume control