Audio Issues when sampling vinyl

When I am attempting to sample vinyl with the mpc ren I often get a muddied and distorted play back. This occurs whether I am recording the sample or simply listening to the record in search of samples. I am running the turntable directly into the mpc, and have audio output running from my iMac into a stereo. I am new to the mpc world and would love any insight as to why I am not receiving clear audio from the turntable. On a side note the audio always corrects itself and almost seems to "catch up" with the lagging it seems to be doing. Any help would be greatly appreciated. Thank you.

Where is your "direct mon" knob positioned?

If you are listening to vinyl only, full left. When sampling, full right. If you want to hear vinyl and your beat, somewhere in the middle....