iPhone digital audio out?

I would like to play music on the iPhone but retrieve it digitally so that I can decode it using a separate DAC. I have several iPhones (long story) but would prefer to be able to play music through digital out via using the iPhone 6 due its 64GB storage.

There were some digital docks, some with built-in DACs, but very very few with the lightning adaptor. I understand that one method, using the camera connection kit, no longer works after iOS8.

Arcam makes a lightning-equipped dock with digital out for $300 (though it has its own DAC).

Has anyone else found a way to play audio from a recent iPhone into a DAC?

Thanks

Keith.

(iPhones 4S, 5 and 6)