The real issue seems to be that audiophiles want something that is unrelated to actual perceptible sound quality. Instead people want to think that the sound is good, and they have some expectations as to what might make sound a little better. This is why there is garbage like silver-plated cable, expensive power cords, etc. People expect amplifiers to be heavy, so amplifiers use big transformers and such and end up heavy.

Unfortunately, this phenomenon seems to make it quite hard to find genuinely well designed equipment. I would love to get a small A/V receiver with high efficiency, the ability to drive a load of varying impedance from 1-16 ohms (possibly frequency dependent), and better linearity and noise characteristics than I can perceive. Actually buying such a thing is not so easy due to all the snake oil and the fact that almost no one reviews equipment on any objective axis.

There is one genuine complication that I’m aware of: analog audio connections tend to be old, bad designs. RCA is single-ended. XLR is a decent design, but it’s rare in home audio. Speaker wires, in all their silver-plated glory, aren’t twisted. So inductively coupled noise is everywhere, especially at 50-60 Hz. Ground loops are hard to avoid. Unlike RF, audio should have a flat response down to 20 Hz, so cheap, small tranformers are out of the question. Nice isolation hardware isn’t that expensive, but it would still add up if you wanted to build an A/V receiver with a bunch of isolated inputs and outputs. With professional systems, you are much more likely to encounter differential signaling, but you are also likely to have very, very long wires and rather low signal voltages from microphones and such. This can result in unpleasantness like AM radio becoming audible if you have non-linearities that might accidentally rectify the radio signal.

I would like to see the audio world move to digital signaling for everything, but good luck getting everything to interoperate.