i had a somewhat similar issue with my guitar microsynth, there was a constant distorted bleedthrough. turns out that there was a cold solder in one of the slider connections and the input wires were shorting out; i took a chance and worked on it myself but i wish i’d have sent it in for warranty because the bleedthrough still returns from time to time and i have to give it some more attention to get it running again. the other option that i would look into is just returning it and getting the new xo version: smaller, true bypass, LED status (i had to mod mine for LED but i left the bypass buffered) and ehx’s quality control has gone through the roof in the last few years (mine was an older reissue, as i’m assuming yours is if they had to search for the adaptor and ship it from out of state)

lastly: im not sure this is an issue with the bms, but are you using active or super hot pickups? with my input gain set too high, there is a tendency to trigger over and over – thus preventing any real sound passing through. if the pickups are hot enough to overload the input even at the lowest gain settings, then you would obviously get a constantly distorted sound. ive heard passive pickups so hot that they make it impossible to get a clean sound out of most amps, and i cant imagine the micro synth being tuned to accomodate such extreme input. i dont know your setup at all, that’s just a thought.

anyway, i hope some of that helps!