ARC REF 110 amp ohms

8 ohms was the smoothest for ARC VS 115 and 3A Sigs.

8 ohms will work the best with Quatro's.

The speakers are spec'd at 8 +3/-3 ohms, and I would think that the specified tolerance implies that is the range of variation of the impedance vs. frequency curve. So the best bet is likely to be the 8 ohm taps.

Regards,
-- Al

As Stanwal said, it depends on your speakers. I use the 4 ohm tap with my Magnepans, and the 8 ohm taps with my Spendors. I suggest looking at test reports of your speakers, and see what the impedances are at the most current hungry frequencies (bass) and use those taps. Stereophile is good for this info if they have reviewed your speakers. It is really just a matter of optimum power delivery.

I do not have one but logically it would depend on the impedance curve of the individual speaker. Why not try all three and see what you think with the speakers you have, there can't be that many others out there with this amp and speaker combination.