Audio Research Ref 110 vs. ARC HD220

I sell both and have spent quite a bit of time listening to them side by side with Quatros. My preference is for the REF110, especially on the Quatros where I like to run the REF on the 16 ohm taps. It has plenty of power for very loud listening in all but the largest rooms.

The HD220 is a very good amp but the REF110 is magic.

Using the 16 ohm taps on the REF110 with a speaker like the Vandersteen Quatro that has a pretty flat 8 ohm impedance, makes the sound bigger, more open, relaxed and effortless if a little less tight and fast. It's really a subjective preference and you should try it both ways.

Here's an imperfect but perhaps useful analogy.

If you are driving a car with a manual transmission on a road where the speed limit is 40mph, you might have a choice of two reasonable gears to cruise in, 3rd and 4th.

In 3rd gear (analogous to the 8 ohm tap) your RPM is higher and in the power region where if you step on the accelerator quickly the car will be very responsive. But if you continue to floor it you will wind out and red line sooner, not being able to achieve a very high top speed.

In 4th gear (analogous to the 16 ohm tap) your RPM is lower and may be barely at the beginning of the power band, so if you step on the accelerator the car will be a little less quick to respond, but if you continue to keep the pedal to the floor you will be able to achieve a much higher top speed before red line.

Hope that helps.