Agreed: CAT6 ruggedized to the required degree would cost the same. Then you would need POE to power the ADC and DSP at the stage end, which would also need to

Agreed: CAT6 ruggedized to the required degree would cost the same. Then you would need POE to power the ADC and DSP at the stage end, which would also need to deal with microphone interfaces which have remained compatible since 1950 -- so there's 73 and counting years of working equipment that people already have. You can get nearly all the benefit at the cabinet end of the cable runs.