I had the biggest “WTF is going on” moment with gear yesterday. I did a barter trade and got my hands on a Lifeforms SV-1. My first bit of eurorack. I plug midi out from OT into SV-1, audio from SV into desk. I turn on the SV-1, some terrible humming, weak signal and the output from the SV-1 was somehow being picked up by the OT’s main outs (I had tested the SV-1 elsewhere before the swap). I disconnected the audio out from the SV-1, and the audio signal from the SC-1 was still being picked up by the OT (nothing hooked up to the audio ins)!
It put me in a state of confusion nervous shock for a minute or two until I figured it was a grounding issue. I was also afraid it could have damaged the Lifeforms. I plugged the Sv-1 into another strip and to my great relief all was fine: well better than fine because to my ears the SV-1 sounds absolutely fantastic. From shock and fear to euphoria in the space of five minutes!
