I have a computer system in my shop office. I have one of those cheap external hard drives with MP3 converted music on it. I have a cable that goes from the headphone jack on the computer to RCA plugs that go into the a home stereo system. I set the Stereo system to Line 1 IN. The sound from the computer then goes to the stereo and out to the speakers. I can listen to music from the computer or regular FM. For FM, I bought one of those cheap external antennas and place it in the window. It works quite well there.
My stereo is new enough that it has bluetooth capability so I can get music off my iPhone into the system by choosing bluetooth on the Stereo receiver once it has paired with the phone.