Pretty much, I had this old pair of headphones with a broken headband, so I took the speakers out of the headphones and put then into some earmuff type things (for shooting guns, and noisy yardwork and such). They actually work fairly nicely, but I don't remember the headphones having the lack of bass that they now have. I'm thinking that they material in the earmuffs for absorbing outside ambient noise may also be absorbing some of the lower frequencies.

Does anyone who knows headphones/sound stuff better than me shed a little light on the situation?