so if they are the 2 ohm per coil, DVC subs, you either need an amp thats 2 ohm or 1/2 ohm mono stable or one thats 1 ohm or 4 ohm stereo stable. Most "mono" amps are ones that are already bridged internally and therefore only have one output channel. I did 2 of those same subs on the Power Acoustic LT 980/2 running at a 2 ohm bridged, and dam it hit hard!
btw
Some thing happens inside a radio. Ever wonder why you can almost never bridge a radio and the speaker outputs are high in the THD? They are bridged already and cant be bridged again, just like a 4 channel amp cant be bridged into 1 channel