My sub is making a humming sound

Hey austinpippen,
The noise you are experiencing is due to your rca plug shorting out causing a loop, in outher words, bad earth.
Try getting a noise filter, you take your rca plug and plug it into the noise filter, then wire it to the amp!
you can try a ground loop isolator or relocating your ground [earth].
I hope this helps you out.
Fingers crossed.