Just built the HexInverter 'POSTMAN' Quad A-R and two Stroh PICO VCA to provide four independent modulation sources. These will be used in conjunction with the Moon Modular 524/A Quad LFO/Assistant for my Synthesizers.com BOX66 project.
I've tested the Postman and Dual Pico VCA with one of the Q106 Oscillators set to LOW and the effect is amazing feeding either Linear or Exponential FM on another Q106 set to audio rates.