Ipod nano 3gen sound problems

Yesterday I get an ipod nano 3 gen from my uncle. He was using it one month in Uk. It was formatted in mac osx and i must done format in windows vista to use it and I updated software to 1.0.2. After that i have problems with sounds in ipod nano. In every song vocal is very weak and some other sounds are missing. Also this problem occur in movies. I tried listening music with 5 headphones and results are the same. Music and headphones works perfect with ipod nano 1 gen. Restores and restarts are not changing anything. Uncle sad that when he was using ipod it worked with no problems. I really need help and sorry for my bad english.
Greetings sebaq

Message was edited by: sebaq