PLX 500 - Low sound

I just bought a PLX 500, the sound is very low.

I have another turntable too, but that is not as low in sound as the Pioneer. What am I doing wrong?

There are no ground on the Pioneer. When I put it in the phono connection, it is just buzzing real loud. But when I switch to another connection the sound is clean, but very low. I can actually push the volume to the max and its not loud at all. With the other turntable (from Technics) I can't get above 20% volume, cause it will get loud like in a discoteqe.

What can I do?