For those looking for an equalizer now you can use Airfoil and play Spotify through this program.
Another key benefit is that you can also play through multiple speakers in sync simultaneously for whole house music. For example I have an
Airport connected to main music system and an airplay radio in kitchen. Can play Spotify music through both and listen to music throughout house. Can sometimes drop out. But this is related to quality of wireless in home.
But would still prefer in Spotify had EQ built in.