mp3 player for 2016 Subaru XM radio?

When Subaru decided to build XM radio into the dashboard they decided that a single disc player was enough for me.
I was used to playing my private music selection with the six disc player in my '09 Subaru.
So I wonder if there's an mp3 player I can connect that will replace that old 6 disc player in order to have my private music collection for long drives.
I'd appreciate hearing about what players will work and also receive instructions about how to connect it.

Thanks.
Newby, Don