Hm... can you specify a bit more what exactly you're after?
Midi output, input, frequency analysis, synthesis, post-effects, and so on?
Whenever working with live sound, be it analyzing or generating it, you will need great speed. C++ can handle that, and so could C and C# I guess. Java I am not so sure about, seing as it is an interpreted language, but on the other hand it is used for all kind of things so it might work. DarkBASIC is not really good for anything to do with realtime audio processing, as it is simply too slow.
If MIDI is what you're after, the speed is much less critical since you will only have to interpret / generate a low amount of 2- or 3-byte messages at a pretty low rate when compared to high resolution sampled sound.
I myself have written a plugin to ease the handling of midi streams from DarkBASIC, which you can find
here. Of course, this kind of thing can be done with pretty much any language worthy of its name.