You can use an Amazon Echo device with its 3.5mm output. It will show up on your network as a Spotify connect device controllable by your phone or better yet by another Amazon device located somewhere in your house. Just name the device the name of the room it’s connected to and tell Alexa to “play U2 on Spotify” in the room you named. In addition to Spotify you can control Pandora, Sirius, internet radio and lots of other services. Easy and cheap!