MR816CSX 1/4" outputs pulsing distortion

OK…i am stumped. This is a strange one and i’ve spent a week trying to figure this out with no luck.
Cubase Pro 9
Line6 PodPro

I am simply trying to “re-amp” a clean guitar channel in Cubase by bussing it out via a Direct Out (1/4" MR816CSX output) using an unbalanced Hosa 1/4" cable INTO the LINE LEVEL INPUT on my PodPro for amp sim.
For some reason, i am getting what seems to be some extra noise being outputted the 1/4" outputs. BUT ONLY when plugged into the PodPro! Stay with me.

I tried testing the MR816CSX 1/4" outs into a Behringer mixer = nice clean signal, everything fine. So i know my audio in Cubase bussing out the Direct out works just fine, no weird pulsing white noise.
I tried another sound source into my PodPro such as Youtube audio from my MacPro patched directly into the Pod and that result was exactly how it should be…youtube audio but with the amp simulated distortion of the Pod. And when the sound discontinues, so does the distortion from the Pod.

BUT…when i try to go DIRECTLY from the 1/4" out of the MR816CSX INTO the PodPro, 2 things happen. When i hit play in Cubase, the audio sounds as it should be, dirty from the amp sim in the PodPro. It works. BUT WHEN i STOP playback…this WEIRD pulsing distortion starts outputting from the PodPro as long as the cable is still connected from the MR816CSX! Disconnect it, and the noise stops. Plug it in, and there it is again. This tells me something extra is being outputted from the MR816CSX. But why do i only hear it when connected to the PodPro and NOT when the MR is connected to my Behringer analog mixer??

NOW…here’s the best part. If i hit play in Cubase, the audio plays perfectly through the PodPro with nice guitar distortion AND THE PULSING WHITE NOISE IS NOT HEARD, UNTIL i hit STOP! Its almost like some kinda noise gate effect is happening here.

At first i thought it was a digital word clock issue so i tried using a BNC cable between the MR and the Pod, but this made no difference. And since i’m NOT using the digital in or out of the Pod (just the analog line level in), i ruled out digital word clock as being the culprit.

The ONLY thing i can think of is something extra being pulsed out the 1/4" outputs of the MR816CSX that i am NOT seeing in the MR Editor, which i have gone through a thousand times.

So, recap…
MR 1/4" outputs FINE to mixer
MR 1/4" outputs weird white pulsing noise when plugged into PodPro line level input.
Weird pulsing white noise goes away when Cubase is actually playing back.
Weird pulsing white noise comes back when Cubase is stopped.

Any advice would be greatly appreciated.
Just wanna re-amp clean guitar tracks into my Pod Pro.

Sounds like you have a feedback loop.

I know…its weird. Can’t figure it out.