You need to decide if you want to go with XMOS USB technology or the newer Ethernet technology for input to the DAC.
If USB, then it makes sense to spend a lot on a server, like Antipodes or Aurender N10 etc.. These are optimized for good sound quality with USB.
If Ethernet, you can achieve even better audio quality using a MacBook pro or a Mini running Jriver. You can also run other servers on the Mac like Minimserver. You can alternately use a lower-cost server like Bluesound. Because you don’t need an expensive server, you can afford to get a better DAC, better cables and maybe even a Plasmatron AC voltage regulator.
I would highly recommend Ethernet input interface and Balanced analog outputs. If you get a DAC with a good volume technology, then go direct to amps and forget the preamp. Here is one with good volume technology:
https://www.audiostream.com/content/empirical-audio-overdrive-sx-ethernet-dacpre
If you want a REALLY low noise floor, make sure everything is galvanically isolated to break all of the ground-loops. Ethernet takes care of that. For USB, you need to make sure the interface is isolated. For analog outs use this:
http://www.empiricalaudio.com/products/final-drive
Also, consider whether you are happy with R2R DAC and 24/96 PCM or do you need 24/192, MQA and DSD playback.
Steve N.
Empirical Audio