Trying to Reamp and am getting horrible feedback?

    I tracked some guitar via spidf so I have the processed track and the DI separate. I attempted to reamp the DI signal and get a horrible feedback noise as soon as I change the input source to "Return Input Reamp". Now as far as I know everything is routed correct with a cable coming out line 3 of my apollo into the return on the back of the Kemper, with the DI output in ProTools matching. I have tried 2 cables with the same results, and have also tried plugging a guitar into the return of the kemper and got a signal. Clock source is set to SPIDF in the apollo and the actual tracking sounds great. So as far as I can tell it's not the cable or the Kemper, but likely some minor detail I am overlooking. Any ideas?