I currently have two 800W 12" Subs running from a 580W 4 channel bridgable amp, obviously i have bridged the 4 terminals to give 1 feed for each sub. I want more room in the boot and want to ditch one Sub and run a single 12" sub, i can switch the amp feed so that it recieved a MONO signal from the headunit, could i then run the 2 bridged sub cables to a single sub?

I can set all the channels to have the same level of Gain on the LPF.
I dont see a problem, perviously the 2 subs were underpowered from the amp getting only 240W each this way one will be getting more or less what it should.