I've plugged a computer into an amp, using a 1/8 inch male extension cord, into a female adapter, that adapts into a male microphone 1/4 end. That being said, the amp sits at about half volume all the time because there are other things that play on it. (This issue is not flexible, nor is changing the amp)
The problem is that now, even when I mute out the computer, you hear some static in the background.
I was wondering some about some solutions (preferably multiple).
Can you connect with S/Pdif? or Optical Digital Out? If you can, that would be the best solution.
If not, check your output is using the line level output of your computer and not the headphone jack. If you don't have a line level jack then I would expect there to be some noise due to the impedance mismatch.
I've had great success removing noise from the power supply of a laptop into a mixing desk & amp by connecting the computer through a couple of filters I bought from Jaycar. http://www.jaycar.com.au/productView.asp?ID=AA3085
Having said that, I also used a behinger external USB sound card because the computer didn't have a line level output.
PC sound connections are notoriously noisey; especially on-board jacks.
If possible, ensure that your output jack is set to line-out instead of speaker-out; as this should disable the sound adapter's amplifiers (if any).
The best option is to get a quality external sound adapter (USB or alike) for your computer, preferably with it's own power source (i.e.: not powered by USB).
Hope that helps...
This may or may not fix your problem but it's quick, simple and solved mine. After 4hrs of swapping cables, isolating everything and trying everything you can imagine, all I did was put a 2-prong adapter on the 3-prong PC plug. Problem solved, silent as can be.
