I have an Ensoniq SQ-80 synthesizer that did something like that. A microcontroller generates 8 channels of sounds from a PCM wavetable, and those are fed into

I have an Ensoniq SQ-80 synthesizer that did something like that. A microcontroller generates 8 channels of sounds from a PCM wavetable, and those are fed into 8 analog filters before mixing down to stereo. But all of the waveforms and envelopes were digital.