wire them seperately so you keep your channel seperation. Wire one sub positive terminal and negative terminal to the amps positive and negative terminal and etc. Dont wire them together in other words. Yes mono amps have only one positive and negative terminal but you can possibly hook two or more speakers up to the amp if it has a low impedance stability. (by wiring them together)
ummm not all mono amps have only one pos and one neg terminal, like my orion 1200D for example, it has two pos and two neg terminals but only one channel. its to make it easier to wire subs and voice coils. even my old punch P3001 had two negs and two pos terminals.