Rogue Cronus Magnum ll with Harbeth 7 speakers

Your speakers have an impedance of 6 ohms and can be safely driven off the 8 ohm taps.  I would set them for 8 ohms and be done with it.

Thanks. I got in touch with Harbeth. They told me same thing that scott_w is saying....try both and pick whatever sounds better.  FYI, according to Harbeth the speakers can handle both 4 and 8 ohms so it's really up to your taste and preference.  Most people seem to prefer the sound from the 8 ohm tap for this model speaker and amp combo. 

in my experience the 8 ohm tap will be a bit fuller sounding and the 4 ohm tap will have a bit tighter bass

Thanks for the good advice guys.  FYI...I tried both the 4ohms and 8ohms and I definitely prefer 8 ohms. 

8 ohm preferred