So let me throw this out there. What if I wire 1 dvc sub in series to get 12 ohms and 1 dvc sub in parallel to get 3 ohms and then connect those in parallel to end up with a 2.X ohm load at the mono amp?
dvc sub 1 in series: 6+6=12 ohms
dvc sub 2 in parallel: 6*6/6+6=36/12=3 ohms
(2) dvc subs...