Yep, tried tested and confirmed here. If you are running it on a classic, Paula etc. works as before. If running it on a "next gen", you need "The Maestrix" which provides a surrogate library to redirect OM's 16-bit Maestro audio through AHI.
The latter probably works on MorphOS too if anybody would care to test it.
Octamed works fine on OS4 with "The Maestrix" installed. I still haven't been able to get it to work on MorphOS.