you can hook up one 2 ohm sub to each channel of the amp which means you will hav 2 2 ohm subs. if u had one sub u could bridge it and wire it to the amp for a 4 ohm load
a 2 channel amp is basically 2 amps in one package. if you hooked a 2 ohm load to each channel it would be 2 2ohm subs making a 2 ohm load per channel. if your amp was mono channel amp it would be a different story...