B_Limo,
Getting back to the real world, Al, Alex and David, thank you! The goal is to get the music from the source to and out of the speakers as accurately as possible. That's the ideal senario so that the music as it was recorded is portrayed as it was recorded. I remember conversations that I had with Chris Sommovigo (Stereovox) and Darren Censullo (Avatar Acoustics) years ago.
Chris said that everything in a cable or component is important. You can have the most perfect transmission wire and connectors in cables, but if the connections between the wire and the connectors is lacking, you're hosed. It's simply, the chain is only as good as the weakest link .
Darren said that the transmission of the music from the source to the speakers can only be degraded, there is nothing that can be added to the original signal to make it more accurate than the original signal.
Anything that masks the original signal can be classified as some form of distortion. It may be tubes adding harmonics (warmth) that really aren't there in the original recording. It may be other things like RFI or EMI interference adding noise perceived as sound and masking important aspects in the original signal. It may be small things like solder connections interferring and not passing the signal correctly. And like Al said, inductance, capacitance and resistance can have the effect of slightly altering the musical signal.
Chuck