I play in a prog/djent metal band. I would like to be able to get some super low sub bass. Not necessarily dubstep/house music sub but I want everyone to be able to feel the bass and to get the rafter shaking a little bit. I'm currently running ESP 5 string basses through a boss ODB-3 pedal, a boss NS-2, a fender rumble 350 head, Acoustic 410 and 115 cabs. I want to get this sub bass but still maintain the punchiness and attack. Should I be looking at adding a cab or maybe just an octave pedal?