A lot more listening under my belt (as well as several hours of playing brown noise thru the HRT to hasten the breakin) and my opinions continue to evolve. At this point, I'm not sure which DAC I like nor which is "accurate". The Duet is warmer and has a more forward lower midrange (quite the opposite of my impressions when the HRT was brand new) and the HRT a more distant perspective. Voices certainly have a "chestier" quality on the Duet and many instruments have a rounder, more present quality. However the HRT gives a slightly more focused, dimensional perspective at times. In many ways the tables have turned and I would describe the Duet as more "tube like" due to the midrange presentation. The bass has more weight on the Duet, but the HRT seems to have a slightly better focus and transparency to the bass (and maybe a slight advantage in extension).
I am struck by the huge difference in the perceived room sound in the opening track of the Reference Recordings Tafelmusik album (purchased as a 44k download from HDTracks - my CD copy was quite scratched up and I didn't have the patience to let XLD try to rip it). In the first couple of seconds before the musicians start, there is a very audible "room" sound (I always suspected the air handler in the church/hall they were using) - it is rendered completely differently by the two units.
The Duet is rounder, fuller sounding, and the HRT is more delicate. Going back to my Marantz 8B analogy (a classic tube power amp from the early 60's for those too young to remember this stuff), the Duet certainly has elements of the magic midrange presence from that mold, whereas the HRT is a more modern, "accurate" type of sound. The HRT might well be more accurate, but I'm not sure I don't prefer the Duet - it has a rather pleasant euphonic effect that tends to involve me more musically at this point.
Of course I have not tried any fancy cables with either of these units and I still have the Apogee cable snake in the way. I really should try to fabricate something to get rid of that cable on the Duet and see what I think.
Not sure at this point whether to return the HRT - I might feel differently when my Woo WA2 tube amp arrives. It is interesting that when I had my Rega Planet CDP (and was using the exact same HD600's, Cardas cables and HR-2 amp), I was often trying to add warmth into the sound. In spite of the reputation of the HD600's, I usually felt the sound to be a little lean compared to my ideal mental reference, so the HRT might not be too far off. Of course I was also using the SAA Equinox cable a lot then as well (which I still have).
PS - One More Thing ...
I think I would say the HRT has a more organic presentation of the soundstage the sense of the musicians being individuals. The Duet is a little less convincing in that regard, but it does a more satisfying job with the individual instruments/voices, if that makes any sense.
Edited by khollister - 1/9/11 at 8:12am