I plug my nokia into my home theater and car stero for audio with a 3.5mm to rca cord similar to this and impedence is only an issue in the car when I am charging the nokia through the cig lighter adapter. This is easily remedied with a ground loop isolater found at your local radio shack:
http://www.radioshack.com/product/in...entPage=search
No issues with charging and impedence at home. I have not tried anything with video, so I cannot speak for that side of these or similar cables.