This review is from: Koss Porta Pro On-Ear Headphones Classic, for iPod, iPhone, MP3 and Smartphone - Black/Silver (Electronics)
An outstanding buy. I am a headphone fanatic/lunatic/obsessive (depending upon whom you ask) and can confirm the consensus here that these are excellent headphones, especially when taking into account their price.
They have a full, extended frequency response, tilted toward the bass, and can easily become a favourite of mine in terms of sound quality: they are a joy to listen to.
Comfortwise, always an important factor with headphones, I find them OK: my bald head does not allow the occasional hair-pulling that the Porta Pros are often alleged to cause, and the clamping force (in any case easily adjustable) is fine, too.
I've dropped one star because I had to return my first set due to a channel imbalance: this second set are perfect.