Head Unit AUX Input?

[Robbo VS3]

Long story short, i have an Alpine head unit, but i don't actually have it here so i can't look at it, so i don't know the model. I bought it new around 4 years ago, and i want to use it in one of my vehicles. Now i definitely know that it does not have a front AUX port, my question is, is there any way i can connect an mp3 player to it using a Red/White RCA cable? Is it possible that this head unit has rear inputs? Most units have outputs, but what about inputs? If i had the vehicle here i would pull it out and look for myself, but i can't, and if its not possible to connect an mp3 to it i won't bother looking and i will just buy another one with front AUX. I don't want to use an FM transmitter, i have been told that the sound becomes degraded with them.

Thanks guys.