FWIW, aus dem Wiki-Link in #1 :
Panning is the distribution of an audio signal (either monaural or stereophonic pairs) into a new stereo or multi-channel sound field determined by a pan control setting. A typical physical recording console has a pan control for each incoming source channel. A pan control or pan pot (short for "panning potentiometer") is an analog control with a position indicator which can range continuously from the 7 o'clock when fully left to the 5 o'clock position fully right. Audio mixing software replaces pan pots with on-screen virtual knobs or sliders which function like their physical counterparts.
A pan pot has an internal architecture which determines how much of a source signal is sent to the left and right buses. "Pan pots split audio signals into left and right channels, each equipped with its own discrete gain (volume) control." This signal distribution is often called a taper or law.
When centered (at 12 o'clock), the law can be designed to send −3, −4.5 or −6 decibels (dB) equally to each bus. "Signal passes through both the channels at an equal volume while the pan pot points directly north." If the two output buses are later recombined into a monaural signal, then a pan law of -6 dB is desirable. If the two output buses are to remain stereo then a law of -3 dB is desirable. A law of −4.5 dB at center is a compromise between the two. A pan control fully rotated to one side results in the source being sent at full strength (0 dB) to one bus (either the left or right channel) and zero strength (−∞ dB) to the other. Regardless of the pan setting, the overall sound power level remains (or appears to remain) constant. Because of the phantom center phenomenon, sound panned to the center position is perceived as coming from between the left and right speakers, but not in the center unless listened to with headphones, because of head-related transfer function HRTF ...