There are two ways to tell if a preamp module is installed;
- The slower tech way : Open the deck and take a look. It sits at the frontmost right corner.
- The faster non-tech way : Connect the deck to an amplifier (line in/CD/AUX or similar level input) and listen.
If the sound is fine, the preamp is present.
If the sound is cold, harsh and at a very low level, the deck has no preamp and will need an amplifier with a phono input.
Martin