I've bought these headphones twice, after each pair's 3-year life expectancy expired. However, seeing as they were only $40 (and I've found them even cheaper under the RadioShack brand), they weren't too shabby.

The bass is pretty impressive for the first half of its life, but gradually deteriorates with time. I found that a solution to this gradual loss of bass is to tape electrical tape over the openings on the outside of the headphones.

This also helps to solve another big problem. You must use discretion with regards to where you are using these headphones because odds are, the person beside you can hear what you're listening to almost as well as you can. This can be very frustrating for both parties.

They don't hold up well, either. I've had problems with shorts in the wires causing one of the speakers to stop working, the ear cushions gradually fell apart, and on my second pair, the mesh layer between the speakers fell apart and both speakers fell off of the headphones.

However, if you think three-years of average sound-quality is worth $40, Koss UR 40 headphones might be for you.