An incandescent bulb is essentially just that, a torch.

I have a hard time believing that all studio equipment and fluorescent ballasts suffer these hum problems, though it may be a tough issue to overcome in a home-based setup.

I just did a really quick Google and found one page (from BC Hydro) that actually recommends old-style Magnetic ballasts for recording studios. The high frequency of the new electronic ballasts is what they claim causes the interference. CFLs are all electronic that I know of.

http://www.bchydro.com/powersmart/techno...t_ballasts.html