Tried VirtualMidiSynth with some old software and it is indeed great.
I used the
Evanessence2.sfpack wich I think is really great.But it has 1.2 !gigabyte! when decruched. So expext WinUAE to lag for a second or two if the midi port is enabled the first time.
Octamed Bars&Pipes and MusicX work fine.