After having done a few tests, I think we can safely say that the Arkos player is better than the MYM on pretty much all points, except the number of available songs.
I made a small music demo using the 6502 Arkos player that both Xeron and ISS used for their demo and game, in the same format as the original MYM demo so you can easily see how to play these musics from a BASIC program loading them from disk.
https://github.com/Oric-Software-Develo ... sic-Player
Nothing brain blasting, but it compiles out of the box with the OSDK, and I guess it's what I'm going to use for Encounter.