So I've had my Event TR-6's forever, but recently switched from unbalanced cables to balanced because of my new audio interface. Now maybe they used to squeal too and it just wasn't noticeable, but ever since the switch, the left one has an intermittent squeal (almost like the kind you used to get if you had your 2g cell phone near the speakers). It happens when there's nothing playing. I think it happens when there's stuff playing too, but I'm not sure, kinda hard to tell.
 
Everything in my setup is hooked up to one high quality surge protector/battery backup and one outlet in the wall.
 
I'm not the kind of guy that knows how to check for line interference and that stuff, so I was wondering... These balanced cables I'm using, I just had laying around... Is this the kind of thing that could be caused by crappy cables? If so I'll just go buy some new ones and see if it works, but I figured I'd ask around first.
 
Thanks!

You didn't perchance happen to purchase a buss powered USB interface? 

yes sir. Focusrite Scarlett 2i4.

You should definitely get some new and good balanced xlr's.  Also, get a ferite USB cable as well if you don't already have one.  I suspect your cables because one side is OK.
 
Can you hear the sound in your cans thru the 2i4 w/o connecting the USB to your PC?  If not, then you may be picking up the sound of your power supply through your cables.  
 
 

OK thanks for the advice. I'll definitely check into switching to good xlr cables (balanced XLR to 1/4" right? that's what my output on the interface is)... As for the USB cable I'm just using the included one. I didn't know there was really a difference in other usb cables, i thought usb was kind of all created equally when not used for charging something. I'll look into that too.

You want balanced xlr to balanced 1/4" phone (the 1/4" will look like a stereo plug).
Read about USB ferrite cables here:
 
http://en.wikipedia.org/wiki/Ferrite_bead
 
 

ok so make sure it specifically says balanced on both sides. cool. yea the cables i'm using now honestly were just just hand me downs so i bet that's really the source of the problem.

I think I warned you about bus powered interfaces in your thread where you were shopping, sorry if I missed passing that along. It is a huge reason I went with the Scarlett 6i6 which is not buss powered and only a few dollars more. My friend bought the 2i4 and has the squealing too. He just ignores it I guess. I told him about the USB cable trick.

I remember you commenting yea. I just really wanted to go for simpler. I wouldn't have been against a separate power cable, but I really don't need so many ins and outs.... I still haven't even hooked my guitar into In #2 since getting the whole thing setup! haha. Plus I read a million reviews that all loved the thing. That being said, it's honestly something I can very much live with and overall I love my 2i4. The only time it's a problem is when my girlfriend needs to record voice overs, I need to just turn off that left monitor and then the room is nice and quiet.

Hey if it's not in the headphones that's good, my friends was in his headphones.
You are using headphones for overdubs,, right? Using live monitors would leak big time into the vocal track. I know some people hate headphones, but I'm pretty firm on that aspect.
Apparently a ferrite? USB cable works to get rid of the noise. It's some kind of USB grounding issue and not all computers and/or USB ports will cause trouble.