External DAC

[StefanB]

I think that, the raspberry shield must be compatible with pine board, because it's the same I/O connector.
The pine board have I2s output, you can use for audio project. you can use too PCM5102 from TI.

The Pine A64 board has its own I2S bus include I2S data in and out pins and SPDIF out pin, the audio project should be easier than RP.

The first RPis had no I2S, but the RPi 1 PCB Rev. 2.0 added the P5 header which has I2S CLK/FSYNC/DIN/DOUT as alternate function on GPIOs 28-31.
RPI B+ and RPI 2 moved this signals to the extended 40 pin header (previously 26 pins).

Unfortunately the Pine has I2S on the euler bus, not on the RPI header, thus it is not fully pin compatible.

On the plus side, the Pine has the I2S master clock signal which is required by some I2S DACs.

The pine also has the S/PDIF compatible OWA (one wire audio) which directly connects to an optical transceiver (~5 €/US$, plus some caps/resistors).

Last but not least the Pine has a proper DAC built in, compared to the RPis crappy PWM based, ~12bit resolution onboard audio, so probably you don't have to use an external DAC. (Caveat, measurements pending ...).