What External DAC pairs best with Audio Research Equipment?

I think a nice R2R DAC would increase the soundstage, the Denafips Terminator 15th or the Terminator 15th Plus (for a bit more money) would excel at that. The top end is also very detailed. It had avery positive review at THE Absolute Sound. 

Based on your response to soix, it sounds to me like you are not seeking more warmth for an already warm system. I have not heard any of the DAC’s listed, but from what I know, the Weiss would likely bring some sparkle and detail to your system.
 

My speakers are pretty laid back and I was running them with a warmer Merason DAC and I liked the sound. But I recently introduced a Bricasti M3 to the system and am very much enjoying the more incisive presentation. 

If you are using tube preamp and amp , it’s worth adding a solid state DAC . My choice is the new schiit Biggy. Audition it return it if you don’t like it. It might synergize with your system. My guess it will work. That’s what I did my schiit gungnir Raysonic cdp as transport , audio research preamp and mono block tube amp and it took away softnesss and added good bass and transient.I am amazed.

Audio is full of surprises , you will never know till you try it. Most of my success mostly is when I least expected the gear will work on my system.You have to invest time trying yourself. Agoners can guide you at the end it’s  what you like.

I use a Ref 5SE in my system with a Bryston BDA3 DAC. It sounds fantastic.