It’s the ESS Sabre ES9038PRO 32-bit HyperStream chip.
Back when I worked in the tech world, I had open access to every chip company and was provided reference DAC systems for evaluation. Multi-month evaluations with units from all the top company’s gave a great chance to listen to all the top DAC chips from Wolfson, Analog Devices, TI, ESS, Cirrus Logic, AKM.
The clear winner was ESS Sabre with Analog Devices 1855A as close follower. It appears the marketplace has come to a similar evaluation as the best selling chip DAC’s seem to be ESS based.
The OPPP Sonica is a nice implementation of the chip and well reviewed. I retail bought this particular unit.
Personally I had too many DAC’s due to consolidating households and buying the Spring 3 KTE.
The OPPO Sonica has the ESS Sabre ES9038PRO. The company website has the specs OPPO Sonica DAC
The build quality is crazy good, a big reason they are so popular. One of my good friends has a PS Audio DirectStream DAC and was unable to play a DSD256 recording as it’s not supported on the DirectStream DAC. The DSD256 played though the OPPO though!
The build quality and format versatility and sound makes them sought over. I just have too many DAC’s to keep it.