iPod Classic 5.5th gen inconsistent output

I recently got a 5.5th gen and had no issues until this morning when my headphones and ipod decided to not work together for some reason. I have KZ ZSN Pro X’s as headphones and the vocals feel very far away/almost impossible to hear with them but any other speaker or headphone I hook up to the ipod it works no problem. I’ve tried using the KZ’s on my laptop and they work fine too… I’m really confused has anyone else experienced this?