*DAC

The T+A 200 gets fantastic reviews from those who own them.  I haven’t heard much about the Preamp section in them, in theory, you wouldn’t need your Preamp any longer but the synergy between the Coda Pre and Amp might be better.  I’ve tried a decent amount of DAC’s, anywhere from Node 2i to DAC in a Parasound P6, to MHDT, Krell, Lumin D2 / P1 and some others I’m forgetting.  Price ranges between $500-$10,000.  Once I got into the 5-10 k range, so much depended on the sound signature I liked and synergy of the DAC with the rest of my Gear.  That’s likely as important as price.  Right now I have a PS Audio MKii, it’s to my ears the best balance between detail, nuances, subtleties in the music being highlighted but not being too overly analytical, dry.  Weiss, Lamp are great suggestions based on what you are looking for as well.  Briiscati would be another brand to give a look to, Lumin as well but most of Lumin’s gear are Streamer / DAC combo’s.  P1 / X1 would be above your price range new but get you the details you are after.  

@navyachts 

The description of what you are looking for in sound seems to be the opposite of what the RR dac is offering. I have the Gustard X26 PRO instead of the R26 and I enjoy all the details you may be missing. I used to have a RR dac, albeit the lower end Denafrips Ares II and ended up selling it.

I have a modified R26 with external 10MHz clock and prefer the Weiss DAC204 with the stock power supply. I hear a small improvement by swapping the stock power supply with a linear power supply.

With that said, I find the R26 to be a good value and great for the DIY hobbyist given all the modification opportunities.

Huge R26 Thread

Based on what you are looking for, I believe that you will like the Weiss DAC204. This review compares it to a more expensive, currently well regarded DAC.

Weiss DAC204 Review

@navyachts the suggestion by @ghdprentice to try a Chord DAC is right on target I think. Chord has a great tone, good dynamics and offers few filter options to fine tune the sound. I was running a Chord Qutest when I had the Martin Logan Montis with Pass XA30.8 Class A amp and it was a very good match. 

Also, just my opinion…the Martin Logan 13A are warm and delicate sounding speakers when it comes to the presentation. Your amps are Class A and that in general is going to mellow things out all on its own with sweeter treble and plush bass.
So just some options aside from changing a DAC…look into trying different speaker cables and interconnects. I can’t tell what you’re using now but if the cables are contributing to additional warmth in the presentation, you might still be facing the same challenge with a new dac. Again, just a thought…