Also, it seems to me that I would need
one oscillator per note, which is ridiculous if you want to make something
isn't that CPU intensive.
it depends on the cpu. i have made a 'quick and dirty' cluster-synth
patch (attached) with 192 not very (or at all) optimized oscillators,
which produces about 20 percent load on my machine (3 ghz intel core).
it should run on a atom-netbook. if you need more instances, it might be
too much though. (and less voices do not sound that awful too...)
another possible approach i can think of would be using ifft as a
oscillator bank. though it is probably not trivial to calculate the
spectrum. (or you will have to use a very large blocksize, to get enough