ok did a little more research looks like problem might be that I am operating with two grounds essentially. The cable box going to my powerstrip is grounded to AC outlet and then when I connect it via RCA to my magni, it is also being grounded via the wall wart? Or is this not possible since the magni wart is only 2 prong? I tried plugging both magni and cable box into same power strip and no difference. I will try plugging cablebox straight into the wall and not a strip.
Try this real quick: Just disconnect the cable from the cable box. And by that I mean the cable company's cable that's feeding the cable box.