I’ve been selling used Bose QC2 and QC3 headphones for a little over two years now and have learned a lot during that time. I’ve sold used, refurbished and some new ones. The only way I’ve been able to acquire new Bose headphones was directly from Bose by trading in some broken pairs that I had to them. Many people don’t realize that a smashed up, destroyed QC2 or QC3 headphone is worth at least $100 or more because of its trade-in value. All you need is the serial number from the headphones in order to trade them in to Bose for a new pair, and when Bose delivers the new pair to you it will be sealed in a box with the carrying case and all of the attachments. For QC2s you’ll have to pay about $110 in addition to the trade which includes the return shipping, but that is not bad considering what the headphones sell for new from Bose. So if you ever break your headphones, or completely destroy them, all you need are the pieces and a valid serial number to do the trade to at least recover a part of your investment. In addition you can also trade up a broken QC2 to a QC3 or QC15 for additional money. I’m telling you this because I have acquired enough new headphones to compare them with used and refurbished ones. From my experience I’ve found no difference in the quality of sound between a refurb and a new one. The refurbs have mostly been repainted and have had new (non-Bose) headband and ear cushions put on them. The electronics are normally not tampered with. If you buy a used pair of these headphones make darn sure you have a serial number on them before you buy them. This will prove authenticity and also is necessary if you ever need to trade them to Bose in case they break. Now about noise [URL removed] You can read a good short article about the technology at Wikipedia by copying and pasting this link into your [URL removed] [URL removed] Many people buy these headphones for the wrong reason. The noise cancellation is best for removing or decreasing noise such as what you would find on an airplane, but it is not too effective removing voices in an office type environment. I’ve had s few returns from customers who were disappointed when their headphoned did not work as they had expected cutting out the sound of voices. I try hard to have potential customers test a pair of these headphones out in advance of buying them from me for this very same reason. I’ve also sold to customers who complained that the noise cancelling technology actually hurt their sensitive ears. If you read the Wikipedia article you will see that this technology actually creates noise to counteract noise. I guess aside of all of this information you just need to try to deal with someone you can trust if you want to buy a used pair. All the headphones I sell come with a 100% satisfaction guarantee. My customers have 7 days to test them and return them for a full refund if they don’t like them. If anyone has any questions they can e-mail to [email protected] and I’ll do my best to answer them. I’m not sure how well I’ll be able to keep up with this forum, so it may be best to e-mail me. This is my first time posting anything here and I’m doing it because another member requested me to. I hope EVERYONE has a great day. Now I’m off to meet my wife at a restaurant for lunch. :-)