It's not just cost you shouldn't feel the need to justify; it's also your belief you're getting good separation or soundstage from an amp, or that the Chord sounds better than far cheaper DACs etc. And let's not even mention the M Scaler which is an (expensive) piece of crap which actually makes the signal worse!I caught the DAC bug about 12 months ago. I thought I had found an acceptable "bang per buck" solution with the Gustard R26, a well received R2R box. Indeed it swept the floor with a Topping DX5 and Sabage A20d that used ESS chips and both of those sounded pretty good albeit for around £400. The Gustard is four times that. I'd also add that I am using a Sugden class A amp which brings instrument separation and soundstage width and depth goodies as well.
However serious audio as we know is a demanding mistress. I have invested in a second hand Chord Hugo TT2 and M Scaler and have been listening and comparing with the R2R for about two months. The Chord combo is unambiguously superior in every respect and a big surprise was the improved depth and tonality (colour not colouration) to the bass part of the spectrum. I can live with the frankly odd and obscurest layout and controls.
I am not going to exercise myself or any reader with any cost justification but just listen to kit before you comment. I do believe that the common measurement suites employed are good but only to a point and are currently not comprehensive enough to confirm or dispute with subjective impressions. For example "timing" appears to be a bigger subject than simply measuring jitter values.
Getting back to the science, though - it's great that you've discovered this site, so a big hello, and we look forward to your suggestions for improvements to the test suites so that we can finally pin down exactly why we're failing to see any benefit in expensive audiofool jewelry.