Hey, I'm looking to play with an extension cabinet using the preamp and power amp section of my 73 pro reverb and preferably a JBL D130. The pro reverb is rated at 4 ohms and the D130 I'm looking at is 8 ohms. I understand that there may be some power considerations by not matching ohms? or will I be okay from going from two speakers at 4 ohms to one at 8 ohms? Thanks!