Well, i have an Ampeg BA115 that i plan on taking apart so i can get a 15" speaker that will be able to run with my SWR Workingman's 4004 head. The head is 400watts at 4ohms and 260watts at 8ohms. Im not that good with speakers but what kind of speaker should i put in there so i can play it with that head? BTW i also have a 4x10" on the first jack on the head so the second cab will be going into the second jack. For the speaker on the Ampeg(1x15" at 100watts), how much do you think i could get for it, with out selling the the entire cab, just the speaker? I have only used it for like a half of a year, and was only played in my garage at like half power. And the second thing is what speaker should i replace it with, with the specifications above, for around $100-150?