A lot depends on what you plan to use for a crossover and amp.
Quite a few of the Pro Audio amps, like QSC and Crown will allow you to sum the signals coming into it to feed one woofer. There are also electronic crossovers that will let you sum the sub signal.
If you were planning on using the passive crossover that VMPS offers, you will need to get two crossovers and the DVC woofer in one cabinet. When/if you get a second sub, then you will also need to get a passive crossover and the same woofer built into it.
There is no problem only using one of the coils.
I would suggest the electronic crossover and separate amp as the way to go, however. The Megawoofer is not available in a DVC version and it is sometimes hard to match levels using the passive crossover. If your main speakers are more efficient than the subs, no problem. The passive crossover does have a level control to reduce the main speaker levels. If your mains are LESS efficient, you now have a problem.
