The Yamaha MU2000(EX) and other late Yamaha XG devices were notable for supporting 64 MIDI channels via four MIDI input ports, as could the Roland SC-8850 (the SC-8820 and SC-D70 were 2-port however, and the latter's 2port mode required MIDI to be sent over USB). The Japanese MIDI player TMIDI on Windows was able to address 6 MIDI output ports, which I assume would be like hooking an SC-D70 and an 8850 to the same thing, and that of course means 96 MIDI channels. Of course, I don't think anyone ever did THAT, but 4port was done on Roland and Yamaha's later devices (SC-8850 and the MU2000/EX). The MU2000(EX) also had Korg stuff via add-on cards, so some very late Korg devices may potentially have listened to Yamaha on the 4port issue.

Basically, 2port at 32 MIDI channels was NOT the highest hardware MIDI synths went to.