Purchased it with both c201 and r202 DAC cards. I won’t go into a lengthy description as that sort of review is readily available online.
I own 4 other DAPS (along with 4 tube headphone amp set ups and 4 desktop solid state headphone amp set ups). And 18 headphones. In each case I have had to use an equalizer to fit my old hearing. Well, using the Cayin c201 and r202 this was the first time I did not have to equalize. So right out of the box the sound was detailed, holographic and just the right balance between bass, vocals and high notes. This was with the Meze 109 Pro. Then I tried the very difficult ATI-AP2000Ti and without equalizing is still sounded like listening out of a tin can, but, with equalization, it came into its own and sounded great, using the r202 card.
Anyway, highly recommend purchase of you have a headphone collection and are serious about tuning the setup to get the best out of your investment.