I just lucked out and found a AMP (Amplified Music Products) Model BH420 bass head at a garage sale, but I don't know what OHM the speaker jacks are rated. Can someone please tell me what the OHM rating is for each separate jack? I've read "some" reviews, stating not to go below 4 ohms total, so I am assuming each jack is 8 ohms?? Any info. will be appreciated. Thank you very much.