I owned the Concerto for about two years paired with Parasound JC1 amps and Magnepan MG3.6r speakers. It is a nice linestage, but it is likely not comparable to the Ref-3. I did not compare them directly, but I did compare the Concerto to the BAT VK31SE and VK51SE in my dedicated room. Both BAT preamps were significantly better in almost all respects, save one...the Concerto was a little "smoother". The Concerto also masked low-level detail, was less dynamice in both micro and macro senses, and was not as extended compared to the BATS. Tonally the BATS were more correct to my ears as well. I did love the Concerto remote...solidly built and simple.
I know this wasn't a direct answer to your post, but we are getting closer me thinks? ;-)
I know this wasn't a direct answer to your post, but we are getting closer me thinks? ;-)