When I was a bench tech at Sound Values, they literally bought a semi load of crown amps that were pulled from MRI systems. The audio version was the MA10,000. The output would go down well below 1 ohm. It was a bridge amp that had 4 heatsinks for the outputs. As I recall each heatsink had 10 outputs in parallel. I had a cut sheet where they claimed one amp powered the entire 400 speaker PA at Indy. There was lots of protection circuits for R.F suppression and thermal issues. They weighed about 125 pounds and ran on 3 phase 208 volts.
There was so many of the amps that spare parts were not an issue. I just changed out blown outputs and swapped boards.