just to add to what @GarfieldModular wrote - the befaco Out3 is also available as DIY both as a kit and as PCB/Panel
also note that what I mentioned are actual audio interfaces (or expanders for audio interfaces) - they plug directly into your computer (or expand an audio interface via ADAT)... the modules that @GarfieldModular mentioned are all audio output modules - they connect to an audio interface which then connects to your computer... might save you a bit of time researching!
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities