I have access to a couple of older Gallien Krueger bass cabs, a 1x15 and a 4x10. The model number on the 1x15 is unreadable, and there's no labelling of any kind on the 4x10, so I gave up trying to find info on the web. Then I pulled one of the speakers from the 4x10. Nothing. They're wired in series, but no identifying marks on the speaker itself, so I can't even look up the speaker and do the math. Basically, I have no idea if either of these cabs is 8 ohm or 4 ohm or 27.254 ohm. How can I find out before I plug my Mesa Boogie 400+ tube amp into them at the same time and blow something up? Thanks!