Dell Inspiron 1420 Laptop "headphones sound muffled" Questions

...headphones sound clean it's probably the speakers. If the distortion is present in the headphones, it's probably not the speakers, or anything else in the TV. In which case I would suspect a problem ...

...sound. If so, it's in the wire or notebook. Plug the headphones direct to the notebook to see if it's still there. if it is, it's the notebook, if it's not, it's the 3/8 wire. Run another known good ...

...sound, like the source was stuffed inside a plastic bowl. This is most noticeable when I have my headphones in. I've already confirmed that the headphones are not the source, because I have two pairs ...