Amazon Music High Definition and Ultra High Definition Equipment Requirements

You will need one of these to grab the digital data from the phone to send to the DAC. 
If the USB in the DAC has power, it can power and charge the iPhone. 
https://www.amazon.com/Apple-Lightning-USB3-Camera-Adapter/dp/B01F7KJDIM/ref=asc_df_B01F7KJDIM?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80401905752532&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=m&hvlocint=&hvlocphy=&hvtargid=pla-4584001431258757&psc=1

@mwinkc 

yes, one advantage of Amazon is being able to directly handle many streaming services.  My CA handles only Qobuz and Tidal, everything else requires AirPlay or Chromecast 

Appreciate everyone's input. I believe I am converging on a solution.

Stay tuned for further developments...........

OK: ended up with a Schiit Modi+ (had the necessary specs). Signed up for Amazon Ultra HD music. App runs on my iPhone: can hear music on iPhone speakers. When I connect the iPhone (lightening connector) to the Modi+ (USB C connector) I get nothing downstream to amp/speakers. In Amazon app, there is a screen that looks like it should be showing the Modi+ as a possible output target, but it does not appear there. Tried multiple cable configurations and at least two iPhones and one Apple MacBook Air: no dice; 

Any thoughts?

Can the Schiit do Bluetooth or AirPlay? If so can you get the Amazon that way?  If it works that then the issue the connection.