Audio Research Ref 110 vs. ARC HD220

Has anyone heard these two amps side by side. I am familiar with technical/theoretical differences, but I have yet to hear them in a way where I could compare. I know the 110 is all tubes vs the hybrid design of the HD220. I have an LS26 and a CD3 MkII already. I currently own Vandersteen 3a sigs and am strongly considering the Vandersteen quatros. Given my equipment what are your thoughts about those two amps. I am concerned about the 110's out capabilities since I occasionally like to listen at loud volume levels. Both speakers are in essentially the same price range so price is of little issue. I have yet to see/read a review of the 220 and I know the 110 has been enthusiastically acclaimed.
Thanks for your input.
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.

As an owner of a Reference 110, I would say that if you want the maximum tube “bloom”, musicality, and midrange presence, the REF110 will do a wonderful job, as long as your room is not too large and you do not need to play at extremely loud levels, for long periods. But to realize the full bass dynamics and speed of the Vandersteen 3a sigs, the HD220 can do do a better job. And you can play as loud as you want, for as long as you want, with no output tubes to replace. One other thing: if you often experience some line-voltage variation such as a dip of 8-10 volts or more, then I would also lean toward the HD220. Tube amps need consistent line voltage for both best performance and best service life from the output tubes.
I think, either amp will give you wonderful results, with slightly different sonic “shadings.”
Hope this helps you make your decision.

It all depends on the size of your room and the efficiency of your speakers. In my 14x19 room, with Wilson Audio Sophia 2 speakers that are 86dB efficient, I have had absolutely no problems to rise the volume on my Ref 110 to the head banging levels.
Thanks for your input! I'll have to do a little more auditioning, but I think I'll listen a little more closely to the 110. How does using the 16 ohm taps change the sound/response of the speakers? I currently don't have that option with my current amplifier.
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.
Very much. Thanks, Dave. I wish I lived in your area so I could visit your store. I always appreciate your thoughtful answers. You make this community a better place.
Well I heard them both side by side for a long time. The Ref 110 has more bloom but the HD220 has more slam and bass attack. Also I felt the HD220 is more synamic. For female voices the Ref110 was better. For Jazz and pop music the HD220 was much better to my opinion.

Overall I preferred the HD220. If it is better than a big Krell for example I do not know. I found the sound very good, much better than any ARC solid state amps I ever heard. I found their solid state amps horrible and the HD220 fantastic.

To my ears, Ref 110 excells at microdynamics, purity of tone, Resolution, HF extension and air, soundstage depth and image bloom and musiacal flow. HD220 has more bass slam and articulation + better macrodynamics.