Quote Originally Posted by eyecatcher View Post
Shouldn't be much difference in optical vs coax. I like optical too. It would work. The dock must support the apple USB core audio. Since it is either that or analog audio on the 30pin connector. But it's unknown what bit/sample rate it outputting. I suspect the stream would go down to 48khz or 96 for compatibility from the original source. Imho I would recommend eliminating it from the chain since it could lose some resolution and introduce jitter before the dac.
I don't think there is any audible difference between coax and optical unless you're talking about long cable lengths, where optical will perform better.

If the dock is able to extract the full bit stream from the phone it should output whatever sample rate your file is. If it's downsampling it would have to be doing a lot more processing, and I'm pretty sure the dock isn't doing that. Previous Apple computers have been limited at 24/96 output and the phones may be the same, but that should have no effect on the dock transferring anything that the phone can.

But yes, iPhone and Apple audio stuff can be wonky and I prefer to just use my PC with Foobar or my iBasso DX80 as a transport.