Importance of a DAC's elements

Specifically designed separate streamers/servers usually have the advantage over DAC/Streamers.  I say usually since when you reach the $20K DAC/Streamer category I find the difference is SQ over separates is minimized.  I have even heard some integrated amplifiers where power supplies are all separate as if the one box is really three separate circuits, and the unit sounds better than separates (or at least the separates in my system).   But you will need over $50k and you loose flexibility.  My recommendation is a separate streamer and DAC.  
 

I recommend a streamer/server since I find playback of downloads better in SQ than streaming or at least a buffered input when streaming like on Aurender or some others.  
 

Execution of design intent from streaming input to analogue output is what matters.  For get all about processing technology and streaming platform. So yes annalog output is important since it is part of the design intent. For example, an DAC with a tube analogue output may have SQs different from a SS output, although I fine in higher end equipment that difference is minimized.  Each brand will generally have a signature sound associated with their design intent.  Therefore, you need to determine what are your SQ qualities you prefer.  Do you prefer an upfront presentation or more back of the hall presentation.   Do you prefer crystal clarity or a more opaque sweet presentation, do you prefer dense images or will you be satisfied with lighter images … and on and on.  With DACS, some of my notes are Chord Dave has intense clarity and detail, DCS Bartok  slightly back in presentation with lighter images than say the Mola Mola Tambaqui and Bricasti M1 S2.  Recognize all are exceptionally musical and the choice based on your preferences.  First read reviews.  Pick what you think meets your preferences. Then audition and make a final decision.  
 

in conclusion, I hope I answered your questions.  Go for separates.  Determine your preferences.  Conduct research.  Make a decision based on auditioning.  

PS. Some other notes.  
Quality digital interconnects, analogue interconnects and power cords are a must.  
I find re-clocking between the streamer and DAC gives improved SQ.  An inexpensive re-clocker will work.  You can go with a break the bank re-clocker as well.  I use an inexpensive one.  I also find on those streamers that offer wireless connection and wired connection, SQ is better wired.  My streamer is only wired.  

I also like separating streamer and Dac I figure a streamer is probably a fairly noisy device electrically speaking. So why not keep the conversion process away from the streaming. I also like separates in general you can upgrade one half or the other as you wish, or don't wish.

I've heard both mutibit and delta-sigma Dacs sound good what did they have in common? A robust power supply and a sufficient discrete analog output stage. As they say everything matters.