Tube or R-2R DAC for Tube System

You can't universally connect the preamp stage of a DAC into any power amp and expect great results.  Sometimes you can but not always.  If the amps are too sensitive or you have an impedance mismatch, you may not get a great result.  

Tube vs R2R, again, don't assume all R2Rs are warm and engaging.  I can show you R2Rs that are bright and cold.  The analog stage matters greatly in terms of imaging and soundstage.  Some R2Rs have tube output stages.  

It is tough to make generalizations.  There is a common belief that R2Rs are more musical, have more texture but are generally less detailed than delta-sigma counterparts.  

Delta-sigmas have a reputation for being brighter, more clinical and more detailed and tubes will tame the brightness.  

These generalizations are not true and it really comes down to implementation.  I can show you warm, musical delta-sigmas and cold and bright R2Rs.  The Rockna Wavedream Signature is one of the most detailed DACs I have ever heard (if not THE most) despite being R2R.  Bricasti is one of the most musical DACs I have ever heard despite being a chip based delta-sigma.  

What is your budget?  What tube gear do you have?  XLR or SE?  This will help zero in on some items that you might want to consider.  

I use Chord Qutest with 300B SET with Altec 604E 15" coaxial with compression horn mid-high driver.
Qutest is very detailed and neutral sounding DAC. But with SET the sound is warm.
They work great together.
It is completely different league compared to my R2R Cary 303 mk1 CD player.
I still use Cary 303 as transport.

I know there are good modern R2R DACs around. But I’m not sure that you need to soften sound if you have a tube amplifier.

@idolindian,
You were given excellent and wise advice from @verdantaudio. Don’t over generalize, implementation is more meaningful and worthy of consideration rather than strict R2R vs delta sigma dogma.

"I can show you warm, musical delta-sigmas and cold and bright R2Rs."
Truth!
Charles

Whys is tubes and R2R a choice? Why not both if you happen to think they are to your liking?
Orthogonal decisions.  Like "V8 or red car?"
Anyway i personally think that choosing by technology type is not particularly valid. I can make FETs, BJTs and Tubes sound pretty much alike.  Choose the product that you find musically enjoyable.