I had a pair of QC2's for about 7 years and they were excellent, even after I had to tape the headset back together from being broken they sounded great. I upgraded to QC15 and the 1st pair blew out in 3 weeks - loose pieces in both speakers and poor sound quality. To their credit, Bose simply handed me a new set no questions asked after a store rep tested them. The 2nd set doesn't have loose pieces/rattling bass (yet) but the sound quality is still quite poor. Lots of hissing and the noise canceling is not as strong as the QC2. Have other people had these problems? For those who have also had the QC2 how would you compare the two models? I am seriously looking at comparable Sennheiser's with a Shure in-ear backup at this point.