Oliver: "I personally prefer icons with less color"
I'll have to disagree there. As a graphic artist, I believe color is one of the most powerful tools available for helping make a GUI beautiful, not just effective. Also, I think using more color in the icons will help us stop looking like an FL Studio ripoff when there is really more to this project then that. Based on your sample art, I think we would love to have you contribute your skills though. If worst comes to worst and we can't agree on an artistic direction, you can just work on an alternate theme.
Toby: "Maybe they can improved such that the vertical lines are more bold and visible. I'm also curious of how they look at the destination height of 24 px (there should be no white border at the top or bottom for not losing more details). Once finished, maybe I can help with polishing the SVG file(s)."
In my sample image they are actually copied from 24x24 px exports with no borders. I'll make this improvement and include the .SVG files all zipped up with strings in the next update.