@Raizor, I also tried to do a synth that way and guess what... I have failed completely

, things like importing a .xm file turned into a nightmare for me. And if you are trying to make small intros (<64k) the xm format isn't good for that.
I did make a synth for 4k intros, and I choose to make my own interface, it was "less painfully" for me than working with existing interfaces, it works like Ferris "sonant", where a song is precalc before playing, not really good for musicians but it's possible to make some "music" with it.

Not forgetting to mention that Hellfire helped me a lot on how to develop a useful interface/features for a musician.
Not knowing anything about music and synth, this thing takes me a lot of time to make it usable. So, a help from a musician will make your life better.
Today I know some people are successfully using a combination of VSTi pluggins + editors like Renoise, like for example
Loonies synth, made by BlueBerry.
Still I think having your own interface and format is less painfully than having to deal with features not existing/provided on your synth. But of course, either way, it's a hard task.
Ok, to do a synth is *really* hard, but man, when you hear it's first song done, it's one of the most awesome feeling you could have, it's was really great for me, which was really worth all the pain.
Good luck with your project and never give up
