I have a question since I am new to running head and cab set ups. Is it ok to run a 8ohm 2x10 with a 4ohm 1x15 off of a GK 1001RB-II?? I would think logically that that would equate to somewhere around 6 ohms? Using the logic that running 2 8ohm cabs would equate to 4ohms. I just want to make sure I wont cause any damage to the speakers or the head. Thanks.