Help with Ext. Cab.

[ichinumba9]

Hello,  Anyone have any experience with the GK 700RB 115 combo?  I am looking to add an extension cab to get the most out of the amp which would be 380W and 75W.  The reason I am looking to add an ext. cab is because with the band that I play with now, I find myself with very little headroom.  With only the internal speaker the amp is only pushing 225W and 50W.  
 
I am looking for something that will be portable, loud and still have punch, so I am considering either a 2X10 or a 1X12.  Some brands that I am considering are: Acme, Aguilar, SWR, Eden and GK RBH.
 
Here's what I play: fretless Pedulla Pentabuzz, Epic 4, Fender Jazz and P(w/flatwounds), and homemade 30 scale Electric upright.  I also have a custom Epic 4 w/ filter and Q being built and should be here sometime in May!  Can't wait!  
 
Anyways, I play mainly fingerstyle, thumb with palm muting and some occasional slap and pop and tend to go for midrange punch and play more towards the bridge PU, but I also like the low growly thing with my fretless 5.  So, any suggestions or comments would be much appreciated.  Thanks.
 
P.S. I am also thinking of switching to a preamp+poweramp rig, but that will be in the future and would like to do more reseach on that subject.  

[bigredbass]

ichinumba9:
 
If I were you, I'd add GK's matching 115 cabinet.  If memory serves me correctly, with the biAmp Speakon cable, you could maintain the separate volume controls that GK builds into these cabinets.  I've always found that adjusting the mix between high- and low-pass halves of a biamp rig supplies a LOT of tone control before you even get to the EQ.  I personally would prefer this control that GK designed into this rig instead of a different brand cabinet, instead of mixing several 10s or 12s into the situation that would lack this control.  
 
While you will pick up a 3db jump in loudness by adding a second cabinet, the jump from 225w to 380w will barely make another 3db.  So you may be looking at a 6db jump.  This is fairly substantial and will probably cover your situation.  Plus, nothing anchors a live band like 15s IF you are NOT working with sophisticated sound reinforcement.
 
A preamp/power amp rig is indeed a whole other subject.  
 
Best of Luck,
 
J o e y