I do a lot of composition work, mostly modern acousmatic pieces. I think music is very important to an act, it's one of the things that I think makes you have a leap up to something of a professional standard show. There are a few things (yet to be staged) that I would use that I already have music lined up for and I really think it helps in setting a mood.

Use sound to your advantage, you can close your eyes not to see something but it is much harder to block out sound, make it work for you!

I'm considering starting to create pieces and compositions for a magic/mentalism base to purchase and then use after seeing this thread. Is this something that people might use before I put time into starting it? Not sure if it would work, but basically I could create some music to select from (or create music tailored to your show in terms of length, style, tempo etc.) and purchase then it is yours to use. I see the link above to that site but are there many more? Of course I would have listening samples (that I can't seem to find on the link above) so you could hear it.

FYI: Ensure you get a license or permission to use non-royalty free music.