Thanks for the information, I was under the impression that the Pi 2 also used P5... but indeed it's on the 40 pin header now (http://www.pagemac.com/projects/i2s_amp)

Now if one could repurpose another 2 GPIO pins for bit-banging I2s... there are chips which support multichannel, see http://www.ti.com/lit/an/snla221/snla221.pdf page 5.

If you have the technical skills to make it work it might be worth looking into the AC97 interface on some of the Allwinner boards. I'm not sure anyone's tried using it yet and some driver development will be required though.

Cheers for clarifying that. Might have been the end for hifiberry, iqaudio etc otherwise