Think its honestly using Redbook Audio versions of the above for the Duo port. Also I dont have an MT32 and am not enough of an audiophile to want one for my retro rig anyhow. My DOS machine has a Soundblaster 32 or something. Whichever card came with the big ass Discovery set and the 8x CDROM.
That I got for like 30 bucks or so complete a couple of years back to replace my fuckup when I buggered files with the previous CDROM drivers.
(MT 32 is sweet as shit but its kind of like getting Double Mockingboards for your Apple II machines: Its not honestly the worth the money for most people.)
I tend to turn game music off, especially nowadays where I listen to podcasts while gaming. Back in the days I listened to Classic Rock stations while gaming and thus never cared that the C64 Ultima 5 didn't have music.
Even the games that didn't let you turn em off I just turned the volume down.
And you know, the Duo port is worth a big chunk of change on Ebay. But so is most of the Turbografx/PC Engine library.
Thankfully the best version of Shadow of the Beast was sub 30 price. And is the best way to play that game. It is kind of like how the Amiga version of Defender of the Crown kind of sucks but the Commodore 64 version is fun as shit. Except the Duo has better EVERYTHING than the Amiga original. More colors on sprites, better control, difficulty and continue settings, cinema opening/closing, fucking remix soundtrack that rules...
This kind of stuff is why I give no fucks what platform a game is on. Good is good.
Sometimes its a console port, sometimes not: