Hi, I've just finished the first proto of my new module - a quad VCA based on the SSM2164 IC  8). The 2164 incorporates four high quality VCA channels with logarithmic response and is one of the few highly integrated synth-related ICs which is still in full production (by Analog Devices). The logarithmic response is kind of unusual for a synth VCA and not very suitable for modular synths (because most envelope generators already output exponential CVs - some reading: http://www.synthmuseum