I just picked up a used Fender BXR 300C. It has one 15" in the cabinet, it's a combo but has jack out for second cab. I down loaded a copy of the owners manual but it didn't tell me the ohm rating of the factory speaker. The head is rated 300 watts at 4 ohms and I'm assuming it has an 8 ohm speaker from the factory so that you can run a second 8 ohm cab to get the 300 watts???? I need to confirm this before I try and find the right cabinet to add to this rig. Am I also right in assuming that it is only running 150 watts without a second cabinet. Some help on this subject would be greatly appreciated.