An FM modulator is used to take an audio source (such as a CD player) and play it through a car radio which does not have an aux-input (such as an old car radio).
If you have an empeg car player, and you want to play it through another stereo which doesn't have an aux-input, then yes, this is the device you need. I believe I even mention this one in the FAQ specifically for that purpose.
However, if you think this FM modulator will magically add a radio tuner to your empeg car player, you have it backwards. The clarion FM modulator is not a radio tuner.
If you want to add a radio tuner to your empeg-car, there are two ways to do it:
1) Buy an actual tuner module (they are out of them right now, you can find some on ebay or you can wait for more to be made if they ever do get made).
2) Connect the empeg-car to another stereo which already has a radio built-in. Details on how to connect them are in the FAQ.