I just purchased a GK MB200 as an emergency backup. I use presently an Ampeg PF500 with 2- PF115HE Stack. Can I use the MB200 on one PF115HE cab which is 8 ohms or do I have to use the Mb200 on both cabs which are 4 ohms. Not very savy with the ohms stuff. This is a senario only if my PF500 craps out at a gig.