No extension speaker capability for the RB-112. However, I do own this amp and it is really loud for a 100 watt amp, especially with the SGT engaged.The RB112 seems the obvious choice although I checked the manual and it is slightly larger all round than the PF112HLF, not sure I could stack them...
It would be interesting to find out how the 100w RB112 compares for volume with my PF-50t + PF112HLF.
