Thanks for the details, mine was a second hand, no informations bout who made it, and I am not into soldering but it looked nicely build. Tho' a few people on some modular communities has the same results with theirs.
Very often, the "hiss" comes from the source, at my place bc I often use saturation or overdriven signals, that is where I use enveloped VCA just before the mixer's inputs, when needed, to get rid of the noise, when the muxer is quiet, that is a cool technique to get a clean-yet-overdriven signal. A bit off topic, sorry..