I just bought 2 gallien kruger 410blx-400 watt-8ohms. I need to buy a head and don't know what I should get. I have heard that because of having two 8 ohm cabinets I should buy a head that puts out 4 ohms. I have also heard that a 200 watt head would be enough for both of the cabinets. I am really not too amp savy so I need some help.