A:
Use the 8 ohm setting if your speakers are 6-8 ohms. Your power output to the speakers may be reduced, depending on your amplifier. Even 8 ohms is not a constant since speakers can vary resistance quite widely during playback, so if your speakers are listed as 8 or 6 ohms, I recommend the standard 8 ohm setting, but is it a nice bonus to have the 4 ohm option should you wish to connect 4 ohm speakers.