When my macbook is connected to any portion of my 23" Cinema Display (usb, firewire, or DVI), there is a slight hiss on the audio output that is accompanied by a faint clicking sound every 10 seconds. This noise does not exist when not connected to the display. The sound is always there in the background, even if something from the computer is playing. I can also hear it when using headphones. Any idea what could be causing this? Here is what I have: mid-07 macbook 23" cinema display JBL studio monitors connected via the headphone jack I don't believe power is the issue, everything is plugged into the same power strip and I encounter a ground loop if I plug things into different sockets. Things I have tried to fix this: reset PRAM/SMC toggle settings in sound preferences and Audio MIDI setup windows tried different power strips and different outlet combinations I have resorted to using an Airport express to play iTunes, but would like to connect the speakers directly to the computer. ** I tried using a USB DAC (HifiMeDIY Sabre) in hopes of isolating the noise, but it is still present. I probably should have gone with an external optical DAC to actually isolate any electrical noise.