Changing bass and treble per track should be possible. It should be fairly trivial to add an ioctl to hijack to allow a userland to set them explicitly. This would allow emphatic (or any other userland tag-watching program) to set bass and treble parameters at will.
I think he was asking to change between EQ *presets* not (or the way I read it, anwyay) change to specific EQ params. The former is very doable.
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- Tony C
my empeg stuff