Hi. Welcome back. )
There are quite a few old Amiga users on here who have a lot of experience with music software. I've never used MusicX but I remember back in the day that was the professional software of choice. I recently tried out Bars and Pipes on WinUAE and that passes through MIDI to my PC USB MIDI interface pretty transparently. The Host/IO ports/MIDI setting in WinUAE was all I needed to alter..so..load up MusicX and let us know if it works. If you need a MIDI interface I like the Datel MIDIMaster. You can usually pick them up cheaply on eBay. Amiga soundcards? Don't bother if you've got a 1200. Paula is the best and if you need 16-bit samples then you can use MIDI and a hardware sampler. The beauty of the 500 and 1200 is that in their original cases they are silent. Stealth mode on.
Ok just seen you have a tower. So if you have a busboard you could get a Zorro soundcard (see Repulse, Delfina, Prelude, Tocatta) but all are pretty rare.
