Or: What are the differences between consumer and professional audio?
The majority of “pro” audio gear is pro by virtue of the provision of balanced source inputs and pre-amp outputs. The benefit is ostensibly common-mode noise rejection. Some amplifiers even have an all-balanced signal path from input to output.
Our reading about balanced audio is that only microphones (because of their low level signal and high impedance) benefit from the use of balanced cables. Audio signals in the studio are high, and impedances low, so the use of balanced cables and XLR connectors are doubly irrelevant. The Wikipedia article about balanced audio says “a compromise is necessary between the noise reduction given by balanced lines and the cost introduced by the extra circuitry they “require”. And of course, this extra circuitry adds noise, distortion and cost.
Doesn’t seem like a worthwhile trade-off. It is for this reason that all of REDGUM’s amplifiers have very low input impedances.