Turntable problem

Hello everyone!!!!!!
Last night I hooked up a brand new Audio Technica at-pl120 turntable to
my setup. I had the preamp in the turntable turned on and had the rca
connectors plugged into an rca to 1/4" stereo adapter which was plugged
into one of the channels of the ad/da convertor(behringer ada8000) I
have connected to my motu828 mkII. Everything sounded great!!!! Then I
get up this morning, fire up my setup, put a record on the turntable, and
start to play it, and I notice, there is no low-end, and I cant hear any of
the vocals it sounds out of phase. I have a small mixer(behringer
mx802a) with an rca tape in connection hooked to my setup, so I unplug
the 1/4" adapter, and plug the rca cable straight into the rca tape-in on
my mixer, and everything is right again. So at this point im trying to
figure out what happened, so i plug a single end of the rca cable into the
1/4" stereo adapter and plugged that into one of the line in channels of
the mixer, and it sounded normal again. But If I plug the other rca into
the other half of the adapter, the vocals disappear, and it sounds horrible.
What gives????????????????

Edited by knObtweaker