General MIDI synth
Does Max for Mac have its own GM synth?
No, it uses the macOS builtin one (AU DLS).
Thanks.
Why I don't see that AU DLS from Audacity?
Nor from Reaper?
Now you make me wonder. The doc says
Max uses your machine's built-in MIDI synthesizer as its default MIDI output destination. With the OS-provided, built-in synthesizer, you can make sound without any external MIDI gear.
But maybe it's a shortcut and AU DLS comes with Max?
(TIL you can import MIDI files in Audacity)
15 years ago people wondered as well without a definitive answer.
This was for Pure Data:
Can we solve it this time?
there is nothing to solve.

if you have a mac , simply test it if you don't trust
in existance of Apple DLS synth.
you can also load it as AU plugin into vst~
Thanks
It works in my Mac, but this isn't only to make it work without knowing the base.
Why Apple DLS synth is not seen from Reaper, Pure Data, Audacity, ...
Audacity can't use plugins marked as "Instrument".
Summary from an AI:
The Apple GM Synth is one thing, an AU plugin, but...
Max includes its own internal MIDI-to-AudioUnit bridge. That is why Max can show it like, only like, a midi device.