Uneven speaker wire runs

Keep the wires the same length, use 10awg and if you bi-wire make them a true bi-wire. Two seperate runs. Impedence, inductance and capacitance needs to stay consistant and to do this the wire needs to be the same length. The amp has a different effect when the variables of the wire changes. Two 10awg speaker wires from two differnt mfg's will most likely sound different but the bits and pieces may travel at the same speed with some of the bits and pieces getting smeared along the way. It's like comparing the speed of your thoughts to your vocals with a major hangover to the speed of your thoughts to your vocals without the hangover. Somehow there is less smearing when sober. Believe me, you don't want to start talking about skin effect.

Ozzy is right, if it is for home theater you probably would not notice the tonal balance difference. Plus you could set up your pre/pro to compensate if you heard a difference. In a good two channel setup you can hear it. Especially in the vocals. Good thing that most of the vocals will come from the center channel of your HT.