Sound Servo EZB Not Reacting On Roomba Iotiny

I’m building a talking Roomba (650) and hit a wall with Sound servo (EZB). Hardware: Roomba base, Synthiam ARC on Windows, EZ-Robot IoTiny on the deck, micro servo on D0 (powered by a 6V BEC with common ground to the IoTiny), and the iRobot Roomba Movement Panel is driving the base great. I can manually move the mouth servo with a servo control and via EZ-Script, so wiring/power seems fine.

The goal is lip-sync while ARC speaks. I added the Sound servo (EZB) skill, set Board 0 -> D0, Min=40, Max=120, Scalar tried from 0.5 to 4.0. The Level Value never moves off 0. I tried ARC’s Speech Synthesis (Say), and also played WAVs using Soundboard PC-servo stays still and the Level Value is flat. I even toggled the "stream audio to EZ-B" option in the Connection control, but it didn’t change anything.

I’m starting to suspect this is because I’m using an IoTiny, which I believe doesn’t support audio streaming/output like an EZ-B v4 does. If that’s the case, is Sound servo (EZB) simply incompatible with IoTiny and I should switch to the Sound servo (PC) skill to drive D0 from the PC audio, or is there a way to pipe ARC/PC TTS audio into what Sound servo (EZB) listens to on an IoTiny setup?