This weekend, I got this ES9023 DAC:
http://www.aliexpress.com/item/Audiophonics-DAC-Sabre-ES9023-I2S-vers-Analogique-24bit-192KHZ/1919635539.html
If you buy it: Keep your eyes open! In my version, the black and red wires where interchanged, so I nearly grilled the board. Luckily, I double checked the wires and the description for plus and minus of the current plug.
Connected then to the previously soldered pinheader of the raspberry and it works easily with the hifiberry . Sound quality seems to be better than with the original raspberry sound plug, but I am still waiting for an amplifier and speakers to test it.
