It really could be your keyboard device? I've heard this on too many occasions and unfortunately recorded same. But not to say that the M-Box 2 dozen have problematic input issues. It does. One not try a DI box and plug into the microphone input? If it's still there, it's the keyboard. A lot of them bleed and worse than a woman.

Not a bleeder
Ms. Remy Ann David

I thought of trying that... in fact, I went to go buy it, and thought it was probably something different, so I thought I would try asking on here.. I've tried so many things, except that.. I guess I COULD just buy one, and if it doesn't work, take it back... a specialist at Summerhays Music in Orem, UT told me that he had a lot of guys come in complaining about something similar, and it was just that they had the recording interface too close to the computer and it was picking up the hard drive (this makes somewhat sense, considering unbalanced lines are prone to picking up lots of noise... But, I went home and tried moving the box, but it was the same -- it didn't matter how far I moved the box, it had the same sound... I think you may be right, I'll try the box..

It sounds as if you could also be describing clock noise? This could emanate from either the computer or the keyboard device? Also, if you have a CRT monitor, TV or anything like that around to get away from as many things as possible. You'll find out with a DI if this is coming from your keyboard. And if you purchased a DI purchased a transformer type. Not a transformer less type. You get electrical isolation with a transformer. You don't get that from an active box.

It's sad sometimes. I recorded a killer live rock-and-roll recording with heavy emphasis on one of the keyboards. This wonderful keyboard (whose brand shall remain nameless since I can't remember anyhow) had the most obnoxious lowlevel multifrequency oscillation the entire night. No effective way to eliminate it at the time either. Not even in post. Oh sure, I used a gate. But it was coming through the monitors, the PA and was effectively picked up by numerous microphones. Oh well. The joys of live recording. Thankfully, it was bitchin' enough set that everyone still loved it.

eeeeeeeeeeeeeeeeeek (that's what it sounded like all night)
Ms. Remy Ann David

I'm positive it's coming from the keyboard. I tried moving all components further away from the computer and monitor, and the sound didn't change.. it doesn't matter how far I move it, the sound is the same all around... even if I put the equipment RIGHT NEXT TO the computer & monitor. I am using Mogami low noise unbalanced and monster XLR & Mogami XLR balanced Neglex cables, and in turning up the gain, I hear very little noise when the keyboard is NOT connected... But, what I don't understand is why it DOESN'T make any noise when I'm not running Logic, or any recording program on my computer! In Logic, it's a steady, but kinda quiet eeeeeeeeeeeeeeek! In GarageBand, it's louder! In ProTools, it's about the same volume as Logic... Because of this, I think it might be clock noise caused by the program--somehow carried over the USB cable???