What is the difference between CL2 and CL3 rtaed speaker wire?

Answer 1

Is this a difference in gage?

This is important. Ideally, you don't want to use anymore than .5dB of the amps powerout to drive the signal to the speaker. This is dependent on load and distance.

Here are some max wire runs listing gage, load and maximum distance.

10ga. 2 ohms, 60', 4 ohms, 120', 8 ohms, 240'

12ga. 2 = 40', 4 = 75', 8 = 150'

14ga. 2 = 24', 4 = 48', 8 = 95'

16ga. 2 = 15', 4 = 30', 8 = 60'

Any more than this and you are losing power just to push the signal, causing the amp to thermal off or damaging it.