Yes, if you have two four ohm subs and wire them -2- +2+ you will achieve a two ohm load. Now if you bridge your amp, your amp will now see a 2 ohm load, and when you add the subs, which are now wired at two ohms, the amp sees a 1 ohm load, not good for most amps. What kind of amp do you have?
i have a JBL GTO6000 mainly to drive my components and fronts but i'm a bit poor at the mo so i'm tring to budget and run my subs of this amp to, it's obviously meant for one sub but i think there has to be a way around this problem
check to see if amp is 2 ohm stable- if so it should be ok--make sure your power and ground wires are big enough-also for few days keep checking amp for heat