I think your problem might be that you have two different isolated power supplies hooked up to different parts of your system. My guess is that as soon as you plug anything powered by the Powerbar to the Marantz it's going to start buzzing.

The 2600 has a grounding post according to the literature. If the 1100 has a grounding post (couldn't find anything that says it does)then you could run a wire between the 2600 and 1100 and see if that fixes the problem.

Otherwise you might be able to run a wire from the chassis ground of your TV to the post of the 2600. I'll have to say I'm not quite certain what will happen to your surge protection if you tie the isolated grounds together. In theory you'll be fine but it's probably a good question for Monster.