I’m just trying to keep this as simple as possible. And relatively cheap as possible. The sound from my iPhone and daughter’s iPad headphone outputs isn’t good. The camera connection kit from either idevice to my old Theta Cobalt dac (with usb-coax converter) or my iStreamer is very good. Problem is my iPhone’s screen is too small, and my daughter uses the iPad too often when I want to

Bluetooth is a great idea. As is usb on the go. I’ll have to look into those more closely.
Coincidentally, I was in Target and saw a TV for $80. It had an optical output. I may go that route instead, as I’ve got a Roku Express sitting around collecting dust. The bulk of my workouts are a rowing machine. I’m rehabbing a mid-spine disc injury, and the monotony is killing me. Having a TV/tablet playing streaming some video makes time go by far quicker. I also hit a punching bag often, so if I go the TV route, I’ll just connect my iPhone for music.
I guess I just talked myself into the TV. Cheaper, bigger screen, simpler. All around win.
Thanks for all the help.