Velodyne DD15 - worth repairing the plate amp?

rwwear: this is what I actually have 'sitting on the shelf', reserved for my 'resurrection project Infinity Quantum 2'. Goal is to tri amp (feed the 2 coils of the Watkins woofer with class D, low/mid class A/B, high/EMIT with tube or class A) using active crossover, for which I bought (never unpacked!) the MiniDSP 2x4HD. No idea how it works, or how to use it as a low path for the Velodyne. 

WayTooMuchStuff: Will run it as passive with external amp until EBC sends the amp back. Put the back plate on, need to seal up (silicone) the speaker cable pass through hole. Then get the Class D amp and plug it in, see what happens. 

The mini DSP uses a microphone and computer to equalize the sub much like the Velodyne software. But it is more sophisticated. They also make many other products for home and studio.https://www.minidsp.com/applications/subwoofer-tuning/dual-sub-with-mso

https://www.minidsp.com/applications/digital-crossovers/stereo-34way-xover

Now an unrelated question: my main system (audio, TV) is in an extremely larger volume room (2 1/2 stories high, open on 2 sides to other 2 1/2 story foyer, and one story dining room and kitchen (guessing 1800 sqft plus big volume). I use Dayton UM 18-22 in sealed enclosure driven by LT1300 (taken from Elemental Design A7-450 sub). 

When the Velodyne amp comes back, is it possible to ADD it to the main system and pair it with the Dayton UM 18-22?

Or is it not a good idea to pair a 'controlled' (Velodyne, sealed) sub with an 'uncontrolled' sealed. 

Or worse, pairing two different (any) subs?