They weren't all that innovative, except maybe in weight (in a bad way
Dual 8417 Power amp, and i want to remember they had solid state pre amps. They tried to take on VOX with their number of onboard effects - all sorts of rather cool, but ultimately not all that useful gadgets and knobs.
A 4 ohm load should likely be okay. 8 ohm 15 + two 8 ohm ten inchers = 4 ohm load.
Then again, it could be something else... i've never opened one up. (or seen one in person for that matter)
Rather reminds me of ROAD electronics....
And for the record, the OP hasn't been online in almost seven months.