As a general proposition, shorter runs are always preferable to longer runs. Assuming you have a heavy gauge of wire, however, you should not hear any difference between a 3' and a 10' run. However, as you exceed 10' in length, the cable thickness should be at least 12 gauge. While length is important, there are other factors that come into play as cables become longer. Capacitance, resistance, inductance, and impedance all influence the quality of signal transmission. You might try looking at KimberKable's Web site, which contains a table that shows the measurements for various kinds of Kimber products.
