I have a 400w Yorkville BM400H head. I somewhat understand Ohm's but also not so much. Here is my dilema. The head is rated 400w at 4 Ohms...I understand that I cannot go any lower than that. I have a 4x10 bass cab that states it is rated at 4 ohms. On my head I have (2) parallel speaker outputs which states "total min load not less than 4 ohm". Now I do understand that if I take a 2 separtate 4 ohm cabs then it become 2ohms (am I correct??), but what I wanted to do was take my (4)ohm 4x10 and run it with my (8)ohm 1x15 cab. Can this be done? What would the ohms translate to when you combine a 4ohm and 8ohm? My main concern is that I do not want to fry my head...its a great hardworking head but the last thing I want to do is "f" it up. These "ohm" things are just confusing! Can someone help me please?!?!?!?!