I had looked at this some time ago when I got the CFE but my memory is useless so I need to go into research mode again and have too many tabs open on two browsers ha!
At present I plug the DAC into the 3.5mm input , Bluetooth the phone to the DAC as I haven't the right cord to plug in it seems, even with losses over BT its an improvement. ( I use BT to connect the phone before anyway so can see improvement.) I use the volume on the DAC , have screen on phone on to let me swipe to change tracks without looking , I'm using Spotify playlists am going to Amazon music next for the high quality stream.
When I get the tablet setup I'll use a big storage card to hold music hopefully. Plus stream via wireless hotspot on phone.
If you look into the setup of CFE videos it is explained. I'll get onto that ......
The rest of the stereo setup, amps etc added in is not hard using high inputs from existing signal then out to the speakers.