if you buy an EMS cart, you can have 2 different .gb files which can be different programs (like LSDJ and nanovoice, or a game rom or whatever), but only one .sav file which is a save state OF that program (so: songs, etc.)
im not sure exactly what you mean by "holding synth sounds", as LSDJ IS a multi-synth with 4 separate channels and holds the possibility of literally hundreds of different synth instruments within each channel in each song file, and each cart can hold, maybe 15 - 20 songs depending on file size. If you are talking about samples, you can create your own sound bank for the WAV channel and build 20+(?) different sample kits with whatever sounds you want, provided they are under a certain file-size
hope that helps?
) Does anybody have a more specific range of frequencies to chop for the nyquist thing?
its cool to see people actually focusing on it finally!