For the record, I love Pandora One. I can make my own stations, listen to Pandora created stations and it introduces me to new artists daily.
In the studio, I often plug in my phone to the stereo’s mp3 connection and go. The downsides are I cannot do Instagram BTS shots, my battery gets depleted and it is a drag if a call comes in. My solution, my first generation 8GB iPhone.
Note the “No Service” display next to the WiFi display. My current phone gets freed up and the early iPhone lasts all day on a charge since there is no cellular activity.
Got an old phone? You can eBay it or make a music server. Enjoy.