Weird that Okto maunf is so secretive on internals (DAC chip, op-amps, architecture). Bring up the Amazon or Ali page on just about any Chinese D/A (or similar product) manuf -- Fiio, Topping, etc -- and the "flyer" given you the whole spiel, colorful pictures and graphs to boot ... more than you ever wanted to know.
I've read (head-fi.org) that this Okto uses the ESS ES9028Pro chip. A bit dated now. The 9038Pro or 9038Q2M are newer.
I've read (head-fi.org) that this Okto uses the ESS ES9028Pro chip. A bit dated now. The 9038Pro or 9038Q2M are newer.