Plopping sound through Line-Out, Hex Mac Pro 2010

[Sahib7]

I've two problems with my new Mac Pro.
The one that's discussed here: http://forums.macrumors.com/showthread.php?t=1017977
and an intermittent "plopping" sound through my Line-Out even when the line-out is muted (e.g. while playing a game with headphones).
It sounds like connecting and disconnecting an audio cable.
I've connected my amp via a klinke cable to the line-out of my Mac Pro.

Any hints for a solution?

[Honumaui]

http://forums.macrumors.com/showthread.php?t=1010857

not sure if this is the same ? but sounds like it not sure if its a solution but its discussed :)