Well.. i bought another thing off ebay today, (god im such a ebay whore ) .. ok.. so i bought a Sennheiser HD 280 Pro, something that i thought was essential for me to become a cpl and get sponsored.. then get free comps ^_^ (my dream)
I heard that Grado made much, much better phones for the money. Having never listened to Grados or good Sennheisers I can't say for sure. But from reviews, Grado makes the best headphones.
I'm not too sure about senns, but the Grado SR60's are the very best of the best you can hope to get for under $100 US (they go for about $60). After a certain price point though, Sennheiser does offer better quality - just not in the lower ranges.
Enjoy the Senns though . Since they're used, you won't have to worry about the usual 100 hour breakin period.
That's about average for any high end audio system. The 100 hours gets the drivers nice and flexible so the sound quality gets very noticeably different even after the first 24 hours. After that, the quality improvements are generally felt only by the most sensitive ears...like mine