Which speaker post to use: 4 ohm or 8 ohm?


OK, this is hardly an emergency, but I have an ARC VSi60 intergated amp connnected to Green Mountian Audio Continuum speakers and I'm not sure which of the amp's speaker posts to use. It has 4-ohm and 8-ohm available. The speaker's designeer told me the speakers were 6-ohm virtually across the spectrum. Right in the middle.
I know John Atkinson's measurement column in the Stereophile review of the VSi60 stated that the speaker impedance should be higher than the terminal, implying I should use the 4-ohm terminals. But I've tried it both ways and I'm not sure I hear any difference. So I guess it doesn't matter.
But i would like to hear your thoughts on the subject!
achilles
Atkinson is right, and while you will lose some power with the 4ohm tap, it should be more linear and lower distortion, and a lighter load on the output tube, so longer tube life. That is the theory anyway, if you can't hear the difference, I would stick with the 4ohm, Atkinson is pretty well informed....