usually the speakers and monitors are run seperate from the snake, so noise is not added to your line signals. the signal line to the amps can run from the snake, but i am pretty sure not the powered ones to the speakers.
this is a good read on balanced lines;
"Tone is in the instruments. Technique in the hands. Do what you will." ~quote from some guy at the TGP forum
"Without a doubt, the quality of your instrument will effect your tone, and any pickups, effects, amps, and microphones used along the way will also have an impact on the sound waves."~Cameron Mizell