I'm not strictly an objectivist (I build and use tube amps that measure horribly by todays standards) but when it comes to DAC's I think getting the one with best measured performance is the way to go.
That, and obviously the one that meets the functionality you require -- Balanced or SE ? Volume control/Preamp ? Toslink, Coax or just USB? Remote?
Anyway, you don't need yet another component in the system that is a tone control. There are a ton of DAC's that have a SINAD of 110dB-120dB which guarantee's a fully transparent source. You can mix and match the amp (tube / SS) and/or speakers to tailor the sound.
Various offerings from Topping, SMSL, Schiit Modi/Modius or at the higher end, the okto research dac8 stereo.
It simply doesn't make sense to spend more than that on a DAC.
Last comment, I disagree with the Codex recommendations. It is an OK DAC (I owned one a few years ago) but it uses the ESS 9016 chip which is a few generations behind by now. The headphone output isn't too great either. Any Topping DAC at a fraction of the price will perform much better.