how can i hook up my numark dm1800x 4ch mixer an vinly turntabels to my laptop pc with cubase7. i have a focusrite sound box and all the rca and other chrods too. i use to have a mac with a firestudio to record but its a little differnt can you help me please thanks

Thanks for the input, however we are now having another problem. When I’m mixing my house mix the sound coming from the stereo live is fine however the recording to the computer is having a reverb effect with only the vocals but the rhythm and beats are fine. What should we do to fix this problem?

That doesn’t make sense unless your talking about vocals from some other source (mics) rather than from the turntables or same source as the rythmn and beats.
Again you’re making us make a lot of assumptions.
Perhaps you need to turn off direct monitoring - especially if you’re running over an external mixer.

Took a quick pic of our chain setup. The chain goes Mixer’s RCA Record out > RCA cable > Stereo’s Video/Aux in(for amplification) > Stereo’s high freq RCA out > RCA Y-Splitter > Stereo’s Speakers & RCA to 1/4 RST Instrument cable > Focusrite 2i4 Mic1 in(set to instrument) > USB cable > laptop computer.