@insoc ,
After all too many hours spent in the weeds and reading Rob Watts in considering 'the perfect DAC', I concluded 'perfect is the enemy of the good' - and a modern AKM or ESS-based high SINAD DAC (like the E30) is plenty good enough.
It's nice if you can 'tweak the coloration' to your liking via choice of Reconstruction Filter. I settled on 'Minimum Phase Fast Rolloff' and moved on. (Happened to be for a Qudelix 5k DAC/Amp..a nice device for $110)
http://www.esstech.com/index.php/en...ophile-dacs/pre-tuned-reconstruction-filters/
Edit: It certainly doesn't help that the ESS and AKM manufacturers use different terms for essentially the same filters.
For example, the AK4490 has four kinds of digital filter:
Sharp roll-off filter (ESS Linear Phase, Fast Rolloff')
Slow roll-off filter (ESS Linear Phase, Slow Rolloff')
Short delay Sharp roll-off filter (default) (ESS Minimum Phase, Fast Rolloff)
Short delay Slow roll-off filter (ESS Minimum Phase, Slow Rolloff)