I am new to DJ-ing and seem to be having trouble with my mixer. It is a Vestax PCV 275. The problem is I can barely hear the record that is cueing in the headphones. I have tried turning up the volume in the headphones, but that of course also raises the volume of the record playing. I presume I have everything hooked up correctly, but maybe not. Does anyone know anything about these mixers? Is there a trick I don't know about or is the mixer itself in need of repair? (The turntables I have are Stanton STR8 100's)