Customer Rating: Average rating of 4/5Average rating of 4/5Average rating of 4/5Average rating of 4/5Average rating of 4/5
Summary: Aboslutely The Best Under $80
Comment: Okay, the price of these has gone up since the last time I bought some (I've given a lot of these to friends... I'm wacky about them) but not by much. As was mentioned, they do crap out-- I've had one that quit working and another that broke while I was treating it very roughly. Anyway, I think that these are ideal if your player has an EQ on it. These, contrary to what another poster has mentioned, are *very* bassy. I've found that by plugging just about half of the little holes on the back attenuates the bass if an EQ isn't an option. They block sound quite well, better than any other non-active NR headphones I've used.
The weakness in my experience has been treble-- I use the EQ to boost the treble and drop the bass and these sound spectacular (I have to do the opposite for my Grado headphones). I don't think that you could find anything better for this price (and I've tried). The other nice thing is that if they DO break or get lost, it's no big deal! Pair these with a cheap 1GB SanDisk player (the cheap SanDisks that I've used have EQs) and you have a nice, low-risk investment for the gym or anywhere else where they might be damaged.
As for the poor bass comment-- they are tricky to get seated at first. Poorly seated Plugs will sound tinny and weak.
Give them a shot! Not much to lose here.

Customer Rating: Average rating of 4/5Average rating of 4/5Average rating of 4/5Average rating of 4/5Average rating of 4/5
Summary: The sound is almost perfect, but the problems is the wire
Comment: Very good phone, but the wire is very weak. I had other The Plug before and was better than this one, most strong. But thats ok, the The Plug is very good.

Customer Rating: Average rating of 5/5Average rating of 5/5Average rating of 5/5Average rating of 5/5Average rating of 5/5
Summary: Cheap, Darn fine sound, blocks out most outside noises
Comment: Yeah, you could probably find higher fidelity earphones, but for the price -can't beat'em. I had a pair of these for 3 years before they broke earlier this year - I'd bought them in the airport, because I'd forgotten my ear plugs and didn't want to listen to babies crying and people gabbing. They blocked out the outside noise and had good sound. When, I saw they were still making this product, I immediately bought a new pair. I use these on the local trains and they block out all but the loudest and most obnoxious people and basically allow me to forget that I am on a noisy train crowded with people...

Customer Rating: Average rating of 1/5Average rating of 1/5Average rating of 1/5Average rating of 1/5Average rating of 1/5
Summary: awfull
Comment: these are some of the worse headphones i have tested the sound is horrible and tiny using an ipod touch no bass what so ever. i guess i have not learnt my lesson sony seems to have the best sounding headsets for this price range.

Customer Rating: Average rating of 2/5Average rating of 2/5Average rating of 2/5Average rating of 2/5Average rating of 2/5
Summary: Tinny, underwhelmed, get Philips HE592 instead
Comment: As a long time Philips HE592 user I was looking for something better or at least as good. In a head-to-head comparision the results are clear. The Koss require more power on the signal to create the sound (1.5-2x more). The bass is jittery and the overall sound quality poor. There is not nearly as much bass as the HE592. Compared to the HE592 it sounds like you are listening to the playback through a metal can.