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!
Strong accent, huh? It's 'integrated'. ... :-)

The answers are 'either' and 'try it again and listen carefully, back and forth'. You'll get more* Voltage gain (= loudness) from the 8-Ohm tap, but the bass drivers will be damped better from the 4-Ohm tap.

* 'More' until the amp clips.
Use the 8ohm post for a 6ohm speaker.
I would use the 4-ohm but if you can't tell any difference it may not matter.
Hi Achilles

Check out this thread for some thoughts.

Try both and use whichever sounds the best to you.
Oops, first day with my new fingers. It's definitely "integrated."
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....
Try both. Make up your own mind.
seems like this question is asked every week

try both, use your ears and decide which you prefer
He posted that he cannot hear the difference, so preference may not be the issue, but tube life is, the 4ohm tap driving the speaker is easier on the tubes.
I think the Green Mountian Audio Continuum speakers are easy to drive so the difference is not so apparent but I would try one setting for a few weeks (at least) and then try the other (if you have not done so already).

sorry for my earlier post OP I did not read your post completely...

It seems to me either 4 or 8 OHM uses more windings on the power supply so the quality of the sound should be higher even if tone is similar?

If you cant hear any difference, either is fine.
Thanks for all the input. I'll do one more comparison then if I can't hear a difference I'll use John Atkinson's recommendation.
What type of music or evualation standard(s) are you since you can not hear a difference?
The 4 ohm tap on your Audio Research amp is not exactly 4 ohms. In fact it is closer to 6 ohms. So, it is recommended to use the 4 ohm tap. However, you should still try both and decide for yourself which one you prefer.