I'm beginning to supsect the Y-cable.
If I move the Y-cable, the humm is effected.
I tired with a head-phone extension(really long 1/8mini-stereo to 1/8mini-stereo). It had PC-extension-Ycable-amp, and the humm was far worse, but I do think the extension is a fairly high quality. So, I think moving the Y-cable closer to the amp could have caused the poorer quality.
Does any of that make sense?
I think Monster Cables are pretty high quality, I might look into ordering a new Y-cable?
***edit***
I'm now quite certain the Y-cable is the problem, I have my head-phones hooked directly to the PC with no back-ground (I cant hear my fan!

)
I would like to try to be cheap with a new Y-Cable, any good brands that anyone could recomend?
Logan