I had a disturbing experience.
I used to have a Squeezebox Classic, which sounded too dull through its RCA's.
So I went looking for DACs.
At first I tried a Meier StageDAC, which was too analytical and tonally flawed too my taste; in came a MHDT Havana; nice, but ultimately too laid back. So I got myself an Audio-GD; good tonality, but somehow a little bit mechanical; in the mean time I chanced my Squeezebox Calssic to a Squeezebox Touch without ever trying the analogue RCA-out.
Last month I sold the Audio-GD, since I nitended to buy the Rega DAC, having had a great experience with the Rega Apollo CDP.
But that is not for sale yet, so I connected the Touch RAC-outs.
Wow, that was actually great fun; compared to the Audio-GD and Havana it sounds absolutely less refined, but otoh it is much more energetic and dynamic, Rock is great fun and so is electronic music.
I have to conclude those rather expensive DACs are not really better then the Touch DAC, it is just different flavors; gain depth, loose tonality (StageDAC), gain tonality and smoothness, loose excitement (Havana), loose refinement, gain dynamics and excitement (Touch).
It also depends on he music; listen to electronic music, StageDAC is best, listen to acoustic music, get an Audio-GD or Havana, listen to Rock, the Touch is great.
So in my experience it is not really true that more expenive is better, it seems mainly a matter of different flavors.
(note; this is all on a speakerbased system, a headphone system no doubt gives other results).