small wire introduces unwanted resistance (actually, impedance) so degrades the signal quite rapidly and is a factor of the wire's length. you can get into high finance with just the speaker wire. audiophiles (purists) would say that you need OFC (Oxygen-Free Copper) but that would be expensive overkill in your application. 16 AWG (recommended minimum) is 0.0508 inch or 1.31 mm in diameter. 14 AWG (better choice) is .0641 inch or 2.08 mm in diameter. Considerably larger. i hope that this electronics 101 lesson was helpful.