The Lumin X1 interests me because of that fibre optical network connection. I believe it is the only DAC that has it. Another external DAC I am interested in is the Denafrips Terminator. I am looking forward to someone doing a comparison with the Lumin X1.
With regards to ESS chips, I have not heard the Lumin.X1, but have a lot of listens to the older Mirrus DAC from these guys.
https://www.resonessencelabs.com/ The Mirrus was an incredible sounding DAC. They currently do not have the latest ESS chip (not sure why) and they are dragging their feet getting ROON READY support. However, they may feel the ESS9028PRO chips is more than adequate compared to the latest ESS9038PRO chip. Benchmark Media told me that the difference between their DAC2 (ESS9028PRO) and DAC3 (ESS9038PRO) was negligible. I ended up upgrading from the DAC2 to the DAC3 but I could not tell a difference.
The key point for me with regards to
resonessencelabs is that they know the ESS DAC architecture better than anyone in the world. The engineers at
resonessencelabs were formerly with ESS and designed the ESS DACs. Darko.com mentions this in one of their reviews.
I met the resonessencelabs guys at an audio show and they played the Mirrus DAC with a 20 year old $500 eBay speaker. Just to prove how amazing their DAC implementation was. A highlight for me at that audio show.
I would be surprised if the Lumin X1 was better than the latest top end resonessencelabs DAC just because of the ESS engineering background of the DAC designers.
Saying all of this the DAC I am currently thinking of getting is the Mola Mola Makua with internal DAC option. It is supposed to be even better than the external Mola Mola Tambaqui mentioned a few posts above. It also has RJ45 streaming and ROON READY support.