silly set recording queston

with two different mixers now and two different set of turntable...

when i plug mixer out to the computer it records ok. when i plug mixer out to a monitor it sounds fine. but when i plug mixer out to my computer and record out to a monitor both have horrible hum feedback.

the only solution (as the computer is in another room 40 feet away (is the long cord the problem...no cause its aight when the monitor ain hooked) is to record on the computer with only the headphones to guide me as what the hell is happeneing.

fuckin bull. and i only have access to serato for a very short period of time.

listen off the computer?

ide need another 50' cord to go back to the other room. i just got drunk and didnt learn shit about serato so fuck it. still a shit dj.