Daughter needs something better than iPhone for music. Help!

My daughter uses Spotify as a music source but listens via her phone speaker when at home.  I have an extra pair of Paradigm Atoms that I do not use and assuming she would like these, what's the best way for her to listen to music on something better than her phone?  It's needs to have the ability to use Spotify and power to drive the Atoms.  Am looking for inexpensive suggestions but gives decent sound quality.  Anything is better than her phone speaker.