Noise and hum!? (SOLVED)

[Mix Master Factories]

EDIT! PROBLEM SOLVED, it was my monitor. As soon as I connected the VGA cable the noise appeared.

When I connected my emulated speaker line out (from the amp) to my Mbox I got some noise and a pretty loud hum around 465hz. I didn't even have to turn on the amp. When I removed the amp from the electrical socket the noise died out. But as soon as I plugged it back in the noise returned (I tried different outlets).
The noise ONLY starts once I start Pro Tools. It's pretty quiet with the Mbox turned on, but with Pro Tools not running.
A fun little fact I noticed was that if I plugged it in the Mbox line in jack-input, most of the hum was diverted to the speaker of the amp. If I plugged it into the XLR input on the Mbox the speaker would go quiet and noise came from Pro Tools.
This hum was not present when I connected the same devices on my Acer laptop running Windows and PT 7.2.

Any ideas?

Specs:
Macbook Pro
Mbox 2
PT8.0