ok here are some pics of my setup. sorry if the quality is poor, i took these with my iphone this morning before work.
Well i would try isolating the mini from the carnetix. Also have you just plugged in a set of headphones to the iMic output to see if that eliminates the noise. Just try to rule out each element one at a time.
Well, there's your problem! PSU too close to Mini. Move it far away.
hmm very interesting. i will have to try that tonight. i have pulled my mini out of the glovebox while it was running, with no difference, but maybe if i pull the psu out and mount it somewhere far awayfrom all the sound cables that might be the key. Thanks
onepuff: that is a very good idea. i will try that as well
one more question. do you think all the components should share the same ground?
alright so we have some more information that is making me start to think that this is never going to be fixed. so i followed bugbyte's advice about moving the psu away from the mini. ok so i tried that. i moved the mini out of the glove box onto my center console (for testing purposes only of course) and the moved the psu as far away from anything that had to do with anything related to sound. fired it all up and im not sure but it may have made things worse.
so after that i tried onepuff's advice of testing each component separately. i came to the conlcusion that it is not any one component by itself that is causing the noise. it has to be all of the components once they are connected together. there has to be some sort of grounding issue or something. i don't know i am really running out of ideas here.
Have you tried adding capacitors inline to your audio cables.
My onboard audio card was sending a very loud hiss at high volumes. In an unrelated fix, I changed the case fan (which was running off the MB) and the hiss went away. What does this mean? Beats me, but I would try to isolate the problem: first try the computer with some regular computer speakers, if there is hiss you know where your problem is.. Try taking it apart and removing components (like fans hehe) one at a time.. the mainboard could just suck that way.. If it works well with speakers at least you'll know for sure it's the amps or wiring.
So you still had the noise with the headphones? Did you try it without the iMic just the headphones? Have you tested it out in the house? Have you ever opened up the case? I'm assuming you did if you have the y-cable hooked up for the carnetix. Might try opening it up again and see if something has come loose inside. When i added RAM to mine a screw came loose and was rattling around inside causing it to shut down every so often.