Despite the problems I had setting the Audiophonics DigiPi in operation, which are caused by missing product documentation and poor support from Audiophonics (see http://volumio.org/forum/audiophonics-digipi-raspberry-i2s-digital-interface-t2255.html), I have to say that the DigiPi itself offers a very good value for the money!
You get an optical and a transformer decoupled electrical S/PDIF output capable of at least 24bit/192kHz. Coudn’t try higher sampling rates because of my DAC didn’t support them. The board is based on the Wolfson WM8804,
And as a very nice bonus it comes with an OS-Opto IR receiver! This is easily set up working with volumio following sid_d’s guide http://volumio.org/forum/using-remote-with-volumio-t1923.html. Many thanks for that.
If you’re interested in the DigiPi, you’ve to solder P5 as well as P1 (because of the I2C) and configure volumio to hifiberry digi. The output of the IR receiver is available on GPIO18 (pin 12 on P1). Consider that when following sid_d’s instructions.
Room for improvement may be to replace the oscillator by a dedicated low jitter type…