I'm working on an SNES music program. Set you're emulator so that controller 1 is keyboard, and controller 2 is mouse.
There are two screens. The first lets you adjust S-DSP parameters, the second allows you to create you're own BRR samples. There are 4 "instruments" currently:
Instrument 0: square wave
Instrument 1: 25% pulse
Instrument 2: 12.5% pulse
Instrument 3: user defined
To make a user defined instrument, press left or right. Sample size is (N+1)16 where $0000 is 16 samples, and $03FF is 16384 samples. You can mix up to 4 oscillators. The "wave" parameter doesn't do anything yet so just ignore it. A frequency of $0400 is "normal". In order to hear it, you must press render to update the BRR sample to the SPC700 chip.