There’s no simple answer to this question. Audiophiles will insist that you’ll need expensive hand-made or special cables in order to avoid sound loss past six feet, but professional musicians have opined that quality of analog cables isn’t significantly compromised even at distances of 25-33 feet (10 meters). There is a natural loss of gain with long unbalanced cables, potentially audible in the high frequencies, but it would be most pronounced at around 33 feet and beyond. Digital cables are another story.
How far can I run an audio cable from iPod to stereo before losing quality?

Jeremy Horwitz
Jeremy Horwitz was the Editor-in-Chief at iLounge. He has written over 5,000 articles and reviews for the website and is one of the most respected members of the Apple media. Horwitz has been following Apple since the release of the original iPod in 2001. He was one of the first reviewers to receive a pre-release unit of the device, and his review helped put iLounge on the map as a go-to source for Apple news.