Several years ago I tracked down an external MT-32 unit on eBay, largely for MI2 and Ultima VII. In my experience, DOSBox + MT-32 is the ultimate way to experience Monkey Island 2.
Being intimately familiar with the game from playing on an AdLib, and later on a Pro Audio Spectrum 16 (basically a Sound Blaster Pro), I was blown away by how much I was missing out sound-wise. Given the chance, I highly recommend picking up an MT-32 (or CM-32L, CM-64 etc.). They're commonly found on sites like eBay, and one could probably pick one up fairly cheap if good MIDI audio is important to you, or if you're a fan of '90s PC gaming. For me it was unequivocally one of the best retro DOS gaming purchases I've ever made.
That said, there were a few sound effects from MI2 that were seemingly exclusive to the Sound Blaster mode - picking up the 'sign' outside of Woodtick, Largo's spitting sound, crackling fire sounds etc..
I've always wondered if there's any way to experience both Roland music and Sound Blaster FX? Running monkey2.exe r s doesn't seem to work, naturally.