Amazon Music High Definition and Ultra High Definition Equipment Requirements

I use an Android phone and Chromecast whenever possible from the phone to my Cambridge Audio CXN 60 streamer/dac.  I also have an iPad and occasionally stream from it, but it’s limited to AirPlay, which is CD resolution (approximately).  I also don’t use Amazon Music.

  Can the Bluesound Node stream Amazon over the Network or does it have to use the Bluetooth?

@mahler123 The Node does stream Amazon over the network. It has a limited function app built in for Amazon. If I remember correctly, you needed to use the android or ios app on a phone to create or manage lists and favorites, as the Node UI did not do that...it just played your albums, playlists, etc.

I found that Tidal connect was integrated better.... not wanting to use separate devices to manage or play my music.

Although Tidal and Spotify both offer the "Connect" api, for the best integration on Node, I ended up with Qobuz for the superior SQ. 

The BluOS platform has Amazon Music as a native option within the app…not a casting one like Spotify or Tidal Connect.  The Node N130 is the device to fulfill your objective.  But if all you want is Amazon Music the Echo noted above is more economical, although its onboard DAC may not be as well implemented.

I second the suggestion for the WIIM Mini (or the pro version for that matter.) I’ve had mine since June of last year, and am quite happy with it’s functionality. I bought it specifically because it allows me to stream high res Amazon Music bit-perfect to my DAC while using the native Amazon app on my phone.

The WIIM app is not terrible, but like most other non-native streaming apps, has it’s limitations. That said, it does have some cool features like multi-room audio, content presets, DLNA, and global searching across services. It also integrates with basically all of the music streaming services, which allowed me to compare and contrast the different offerings to see what I liked best for my own needs.

At their price-points, it really seems like a no-brainer type solution that’s worth every penny!

Oh, and not to ignore your question about the Modi+ - That's a fine budget DAC that would work well with the WIIM, but don't think the iPhone would be a great solution at the end of the day.

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