Re-Sampling though a external effects unit?

I want to Re-sample out of my main outputs to my yamaha spx then back into my mpc 4000.

I dont have a mixer so I tried hooking up the output of the MPC to the input of the SPX then back into the MPC input and I get a nasty feedback ring when i choose "Analog in" as the source in the Record page but dont get any sound back from the spx when i choose Main Out as the Record input source.

Is there a way I can Re-sample through an external effects unit and back without a mixer.

Try turning <monitor> to the <off> position. This should stop the feedback loop.

Thanks for the response, I only thought about that after I turned the 4000 off, But.... If I cant monitor how will I hear how the effects box is effecting the sound so I can tweek the settings on the box.