Noise Introduced When Connecting External Monitor

Everytime I try to use an external monitor (screen) with my rMBP an annoying amount of noise is introduced to my studio monitors (speakers). Has anyone else encountered this? I've tried moving things so that my external monitor cables do not overlap with my studio monitor cables. This also happens whether or not my laptop is plugged in. I'm wondering if I may need to invest in a new soundcard so that I can use balanced outputs rather than unbalanced.

Here's my setup:

rMBP connected via USB to Alva Nanoface soundcard -and- Dell external monitor via Mini DisplayPort adapter to DVI cable.

Alva Nanoface to KRK RP5G2 via RCA cables (~6ft long).

KRK monitors are are plugged into same power strip and Dell monitor is plugged in to different power outlet.

The noise starts as soon as the Mini DisplayPort adapter touches near the Thunderbolt port.

I've tried combinations of all USB/Thunderbolt ports.

Help please!

I should also add the when I added a Radioshack ground loop isolator it made everything worse.

Is Alva Nanoface a firewire interface? I had the same issue with my old firewire interface (presonus firebox) and my MBP. I could never figure out how to fix it so I ended up getting a usb interface and there was basically no noise.

Quote:

---

Originally Posted by Nick V

Is Alva Nanoface a firewire interface? I had the same issue with my old firewire interface (presonus firebox) and my MBP. I could never figure out how to fix it so I ended up getting a usb interface and there was basically no noise.

---

Unfortunately, it's already a USB interface.

So the problem was solved by switching to a soundcard with balanced outputs. That was an expensive lesson to learn.