I've been piecing together a system and finally got a two-tier case today with a Mean Well RT-125B PSU that can supply more than enough power for the modules connected. I've quickly noticed that I'm getting a low-volume continuous sawtooth-like base noise coming through the Doepfer output mixer at all times, even if the levels are zeroed out on all modules. It quickly amplifies to interfere whenever I start patching things together. The out is a Doepfer Mini Stereo Mixer A-138s. This feeds into a Yamaha MG10x external mixer, which goes from there to both a stereo receiver and a PC/headphones. I didn't have this issue before when I was working in a 1-tier Synthrotek case, so ... I don't know, I'm too new to know where to start in terms of how to resolve it. I tried removing a couple modules; tried outputting to different lines on the external mixer; tried different cables to mix out with ... it seems that horrible low-volume sawtooth always seems to be faintly there, coming from within the modular build itself somehow. Is it some kind of feedback from the PSU? And if so what would I do about that? Other possibilities?
Thanks for any help anybody here can provide. Happy to provide any info if anyone has ideas but need to know more about the exact setup.