I have an Epiphone Blues Custom 30 with 2x12's built in. The speakers are wired for 8ohms to the amp. I think they are both 16ohms. I would like to buy two valve junior extension cabs (16ohms each) and get them to work with along with my regular 2x12 setup. 4x12's in all. Is there a way to just plug all three cables into the amp, or will I have to wire the extension cabs together? The amp has five output jacks for speakers. 2x4ohm, 2x8ohm, and 1x16ohm.