I own a 1980 Fender Studio Bass amp. It's a 200 watt tube amp and is designed to be used only with an 8 ohm load. It has only one speaker output, but I would like to have two 8 ohm outputs and be able to run it at 4 ohms. Is it possible to change the output transformer to allow me to do this? If so, do any other components need to be changed? Will a different OT change the sound? Any help would be appreciated.