Reviewing the Sony CD player X33ES, X55ES and X55ES series, all are using the Sony 1 bit DAC CX2552Q. This is the same as my low end Sony CDP-M11 CD player.
Reviewing the Sony CXD2552Q datasheet, on page # 7 of 17, you can see the application note. This is the circuit I used to modify my Sony CDP-M11. And, reviewing the X33 to X55ES series, all are using circuitry based on the application note.
The point is, even using lowly CDP or audio source and using datasheet application note, we can have good performance for our audio source.