I've got an old Matrox Marvel G400-TV and decided to do a little test setup. Connected the composite out from the Matrox card to an auxillary composite in on my amp. Sat back and expected to be amazed. I was amazed when the PC booted up. I could not see a thing on the ordinary computer monitor, apart from flickering lines running over it. The TV, kindly, showed exactly the same flickering. And I mean flicker. Not as in hard to read, but simply one-pixel high broken lines. I rebooted, thought that it might help. Same problem. Tried to disconnect the break-out box from the Matrox card. That solved the problem (but obviously nothing on the telly!) Plugged the break-out box back in but didn't connect anything to the composite out. The computer monitor still showed a nice image. As soon as there's a physical connection to my amp, the computer image is completely screwed up. Any ideas about what can cause that? And even more important, any idea about what can be done to prevent it? Any advices will be greatly appreciated.