There may be a very fundamental conceptual problem to address, which I'd say is the notion of transparency.
The original source is the original live acoustic signal (and even that disappears when we go to electronically generated program material which never passed through the air to begin with). After that, everything "distorts" it:
- the air in between (atmosphere attenuates)
- the mic capsule, mic circuitry, mic settings (multi-pattern, pad, hi-pass filter to take out cable/stand bumps, etc)
- the pre-amp, the mixing board (Neve now famous for their great "sound"), sucessive sub-busses and main bus, sends, mastering eng. and equip.
- distribution formats analog and digital--all with their own advantages and disadvantages
- all the playback stages discussed widely on this forum
In other words, there is ultimately no authoritative form of the signal. We don't even hear the same way at the every end of the playback change--everyone's room is different, everyone's physiological hearing equipment is different, everyone's music-decoding brain is different.
The closest we get to a reference standard form of the signal is what the mastering engineer delivers, and even then: how many of those who will purchase the product will have the same room/playback chain as the mastering engineer?--I'm guessing zero. The M.E. delivers what he hopes is a robust form of the signal, providing good music under many varying conditions (and thus containing his own judgments about tradeoffs and compromises).
Yeah, the signal is distorted, no matter what form it's in. The **only** way to get the real thing is to show up and hear Jon Vickers do it live. No comparison, then. (I was fortunate to hear him from 6 feet away, onstage, as a member of the opera chorus). Authority stops there. After that, it's just **which** form of 'distortion' one prefers (AND, can prove that one hears in double-blind, i.e. ABX).