<font color='#000000'>You've got lots of things here, let me try to 'splain them to you...
Engineers, pardon my gross oversimplification...
1/4" TS or RCA jacks - unbalanced, because there is only a signal and a ground. Any induced noise is not removed. Fine for short runs, and less expensive. Very susceptible to ground loops...
1/4" TRS or XLR - balanced, because what you basically have is a positive signal, a negative signal (same voltage/signal, but inverse polarity) and a ground. Because the signal is sent as both positive and negative voltage, a transformer (I'll ignore direct coupling or differential inputs) is used to essentially "phase cancel" any induced noise (which will occur equally on both lines) in the line. The unblemished signal then continues on down the path...
1/4" TRS Headphone Jack - this is a left signal, a right signal and a common ground. Note that this is not a balanced connection.
The biggest question I've always had is why the heck aren't musical instruments like guitars balanced (some are, but it is very rare.)</font>