The MC 2300 is a 300 Watt/channel transistor stereo power amplifier. I don't think he was running a stereo rig, so he probably bridged the outputs in mono for feeding those three Alembic speaker cabs.

That page says the power amp was driven by the preamp of his Fender guitar amp, which would mean that his sound was not dependant on distortion generated by the power stage of the Fender amp!