I can vouch for McIntosh MC 2300's being in a class all their own. In the mid-70's I played bass with Osiris, a band welcomed into the Grateful Dead's extended family because our keyboard player, Kevin McKernan, was the late Pigpen's younger brother.
At one point during this period the Dead members went on hiatus, with many playing in spin-off groups. They let us temporarily borrow some of their Wall of Sound components. For an outdoor gig in the plaza at Stanford University one night I got to play my Stars Guitars modified 72' Jazz through a humungous bass rig: The eq section of our GMT 300B bass amp (GMT later became Gallien-Kreuger) fed one channel of a MC 2300, which in turn powered FOUR stacked Alembic single 15 JBL-equipped cabs. The kind with the beautiful natural finish plywood. Just for good measure, there was either a 2 x 10 or 2 x 12 Alembic cab perched on top of everything! I don't know what the total system impedance was, but as has been noted previously, MC 2300's are able to handle almost any load and not even breathe hard.
I have never experienced the kind of bass this rig put out; not without additional sound reinforcement from a PA! It wasn't just the extreme volume or the sledgehammer wallop that can sometimes become over powering. I've never been a fan of tweeters in bass cabs and those full-range 15's had a burnished tone to die for. The sensation could best be described as similar to going to the beach and wading into the water until it's about chest deep. The energy of the incoming waves (notes) enveloped everyone and was strong enough to physically push the audience back (and me forward...). I can't even imagine how much more intense everything would have been with an Alembic bass in my hands.
Fast forward: Amoeba Records in Berkeley uses a MC 2300 to amplify the background music in the store. You can see it behind the main counter, just humming along. It's huge. None of the employees I've spoken with seem to be aware of how special that monster truly is.
