Can I connect one extra bass box into my hometheater.

[Tumon_]

Can I connect one extra bass system to my 5.1 hometheater.

 

[Reynod]

Possibly but you should use a powered one ... with a built in amp ... as opposed to adding a sub to the existing sub ... which will likely achieve little ... because the amp will unlikely deliver more power.

 

[americanaudiophile]

Adding an additional subwoofer may not solve your problem.
A subwoofer doesn't produce upper bass so if the satellites are too small there will be a suck out. Adding another sub won't fill that hole (usually from around 100 to 200 hz)..
If you want deeper and better bass (not just more) then replacing the subwoofer you have with a good one is better than adding another one. If your sub is not self powered get one that has speaker level inputs that is self powered.