I have the sound to my tv running through my computer via the inline in my audio card and plugged into the headphone jack on the tv. (i had to do this cause my tv has no audio out otherwise and it speakers are crap) Doing this there was always a slight hum that could be diminished by adjusting the audio level of the inline in the computer, it would reduce it but not completely get rid of it. But lately with my new computer, and over the pass few weeks, nothing I do helps. It is an annoying, constant and loud hum so much so that it gives me a bad head ache so I disconnected my tv.

I would really like to solve the problem as the audio from the tv itself is really not great and my pc speakers are 5.1 surround and until I can afford to get my receiver this my only option. I am guessing that it is a grounding issue but not sure how I can fix that.

I would apprecaite any help or advice.

Sounds like a ground loop issue possibly...

Ground loop (electricity - Wikipedia, the free encyclopedia)

Ground loop problems and how to get rid of them

I've found some soundcards create a hum if a mic is plugged in. Muting the mic input might fix it. You could try disabling the tv speakers too, if your tv's menu has the option.