HELP! trying to patch a OTB send/return on MR816! SKREEECH!

Hi-
I have 2) Steinberg MR816x’s - which I’m very happy with- after recording-I generally stay ITB- however I’ve been trying to send a stereo pair OUT thru some outboard gear and re-record it BACK INTO the MR816x…the minute I connect ANY pair of outs to any pair of inputs I get terrible howl and/or a skull-quaking, bone crackling, flutter…I’ve been trying to do this for DAYS…and I’m now beyond embarrassment for asking such a idiotic question…I’ve attempted to scour Gearslutz (and elsewhere for) for an answer…cant seem to find anything other than the fact that the MR816’s inputs are hardwired to the mic pre’s…but still…

I use Logic and DP, NOT cubase!..so I’m limited to the MReditor (I’ve tried muting- panning…same thing)
I have all the MR816x inputs/outputs (and channel 1 and 2 I/O send/return) present on a patchbay
I’m using a macpro

I’m not a engineer or tech just a musician/songwriter trying to get some stuff done!

ANY advice would be greatly appreciated!

thanks!
Greg

I’m having this exact same problem, but with pro tools 10. Did you ever find a solution? I can’t seem to get any help or find any workaround.