Best DAC for around $2,500 or less

The sound quality above a certain level - when all niceties which can mess up the sound are avoided - comes down to the DAC-chip(s).
Everything "Delta-Sigma" is internally upsampling, downsampling, interpolating and "improving" your signal.
The other way would be to have non-oversampling DAC chips, which are not "filtering" or otherwise "improving" your signal.
While many non-oversampling DACs use vintage chips - which can be very musical like the TDA1541 - METRUM ACOUSTIC developed their own modern non-oversampling chips which allow 24/382 "DXD" resolution.
Listening to 2L highres recordings in DXD resolution is quite something.
So my recomendation would be a Metrum Amethyst for +1 1k or the Metrum Jade which is a digital preamp with loudness control (without loosing resolution quality in the process).
I have the Amethyst and it is what a tube amp is to SS.
Not "in your face" but just realistic and relaxed - and with grunt when need be.

The Chord Qutest is the one you need. For much less money, a used Hugo 1 is as good but be prepared to replace batteries every 2-3 years.

I would throw the Bryston BDA-3 into the mix (if purchased used) as it does everything well with all kinds of music.  

Chord Qutest is a very nice sounding DAC and worth a try.

How more on you getting for 2500 that you can't get for half that say an RME ADI2 and then how much better is that over a Denefrips Ares or Topping D90?  Is it worth going to higher priced units?