Thanks for all of the help! I'll be reaching out to those folks soon. You guys are great!
Good luck- let us know what you find out.
I keep looking at the jack added to the back expecting it to be a "preamp out", but it looks like it's just another extension speaker jack? Looks like it's just connected to the jack next to it.
And I still can't figure out how you can use the amp without a rectifier The amp needs DC power to work! Must be more there than meets the eye....