4 or 8 ohm connection for a 6 ohm speaker?

8 ohm has taps have worked much better for me than 4 ohm taps when driving 6 ohm speakers-  and it wasn't even close. 
but this is just a reference point- you really need to test carefully.   

Avanti1960, when you say I need to test carefully you are speaking of the sound quality? Would I do any damage to the output transformers by keeping a rated 6 ohm speaker load on 4 ohm outputs? 
I have settled on the 4 ohm taps as the sound is more complete at the low and softer in the high end. As long as no harm is done then the sound is great. 
Next change will be to upgrade the input or line stage I think it is called but that is for another thread :)

Best to you,

Bill

"keeping a load on" is in reference to never switching taps while the amp is on.
Enjoy :-)

Yes, I normally spend my Summers fishing remote places in British Columbia- this year not possible, so I am missing the fish, beautiful country and charming Canadians.

Looking at the impedance curve for the CS2 measured by Stereophile I would’ve run the 8 ohm taps without thinking twice. The CS2 only hits a minimum of 6 ohms with a dip at about 170 hz whereas it’s at or above  8 ohms from 500 hz and up.  Below 170 hz it fluxuates between 10 and 6.5 ohms. Surprised it has a 6 ohm rating to be honest.

If you’re having better results on the 4 ohm taps then it’s all good...enjoy the music.