…the cables that I use to connect to the 3/4 inputs of the H8000FW are balanced but the synth's outputs are not. This cable probably makes the volume drop by something like ~12 dBm, no? Maxing the synth's output (and with the same TRS/XLR cable), I got something like 5 LED on *some* loud patches. I had to reduce the H8000FW's 3/4 outputs by ~10 dB because after that there is a RME Fireface 800 and because they don't have the same headroom, it kinda freaked!
We are getting somewhere. It's still noisy but not as much.
…What if I a). use a TS cable from the synth into the H8000FW's analog ins, b) have the output levels back to 0dB and c) lower the inputs on the RME FF800 so that it doesn't clip?