Electrons in wire travel at the speed of light - so 14 feet would not make a difference - but being obsessed with symmetry as I am it would drive me nuts knowing there was a difference
Also maybe consider looping the excess rather than coiling as there may be some level om magnetic field build up around a looped cable???
james
Actually, the electrons drift in the cable at speeds like mm per hour.
A signal which has current and voltage consistent with the cable's characteristic impedance will travel at the cable's propagation velocity, for typical zip style that is about half lightspeed.
A signal in a zip style cable where the load is very low impedance in comparison to the cable's impedance, driven by a low impedance source, will exhibit a signal delay which is dependent on the impedance of the load at any frequency. If the load matches the line (about 150 ohms), the velocity will be half lightspeed, if the load is 8, the effective delay will be anywhere from 5 to 50 or 100 uSec depending on length.
A difference of 15 feet could impact imaging in a horrible way depending on the impedance variation of the speaker vs frequency.
I recommend same length.
If a zip is coiled, there will be no additional inductance. The opposing conductors and their currents will create equal and opposite solenoidal fields, netting a zero inductance increase.
If a 4 conductor wire is used, wire opposite conductors in parallel. This will halve the characteristic impedance of the cable.
jn