The sound on GBA emulators is awful! Mappy VM just crackles and clicks and VisualBoy Advance creates loads of harmonics - the output is almost a square wave! Also, is the GameBoy Advance fast enough to do real-time stereo frequency synthesis? Each channel will have two sine waves each, amplitude-modulated with noise added. Will the GBA cope, with nothing else running but a menu to control the frequencies?

If you had a real GBA you might have noticed that the sound output really is crap, pretty much like VBA :)

But yes it should easily handle some simple synthesis. Be sure to stick to fixed point though. There's no floating point hardware.

Oh. I didn't know there was no FPU in the GBA.