can somebody please help me with how the usb port works with this mixer,i got sorato.i got Pioneer cdj800mk2's and Pioneer efx500.when i hook up my efx with rca jacks to one cdj everything work's fine.but when i loose the rca's and use the 1/4 inch jack's and go directly into the 2000usb mixer i get a very low output on the efx.what am i doin wrong?