This is my first review here on head-fi, so please tell me how to improve next time I haven't seen a review for the IE6's on here, and quite a few people have been asking for one, so i thought i'd answer their prayers. First Impressions: After owning several pairs of CX300-II's (where the sound kept going in one of the ears after 3 months or so) I decided to splash out and spend some money on a quality pair of IEM's. I paid £100 for them in HMV Southampton. The packaging was fantastically designed, and the aluminium brushed case was also aesthetically very pleasing, my only criticism is that the case is bigger than any MP3 player or mobile phone nowadays, and it's too big to fit in a pocket. Having said that, the case is solid, and so are the headphones. The jack is tough, and doesn't look like the cable will pull off easily. The part where the cable splits in two is well housed, as is the connection between the cable and the earpieces. They certainly looked like a rugged pair of headphones. Although I've heard stories of people never quite getting the tips supplied by Sennheiser to fit properly in their ears, luckily for me, the medium's fit just fine. I was also particularly pleased with the inclusion of a cleaning tool in the bundle, as there never was a convenient and clean way to dislodge ear wax from my CX300's, which is ultimately why they broke. Time for my first listen.... Well I wasn't blown away. I thought that £100 would've ensured a great listen straight out of the box, however, this was not the case with the IE6. The bass wasn't as strong as I thought it would've been, especially after being used to CX300's which have a dominant and muddy bass; these headphones sounded too tinny for my liking. After being slightly disappointed with the sound from the IE6's after an hour or so, I decided to check out the internet to see if anyone else had any problems, and that was when I found out that the IE series need "burning in" time in order to fully maximise their sound quality. Around 50 Hours of Listening Later... After a month or so, I had begun to get used to the lighter bass on the IE6, but no sooner had I got used to it, the sound produced by these IEM's had transformed. I wasn't listening to a bass heavy track, but the bass had suddenly started to kick in on these 'phones, and I began to think that it was money well spent after all. The mid's and high's had started to become clearer and more distinct from each other, which only enhanced my listening experience further. But the one thing that made me even more excited was the fact that these headphones hadn't finished "burning in". After 200 Hours of Listening... Well what everyone said about these IEM's needing burning in was true, the IE6's continued to get better with every listen, and now I can clearly hear the difference between the Low's, Mid's and High's. The bass was much stronger now, but still very crisp, unlike the CX300's. The treble was sweet, but I still felt (and still do) that it could sound just a little bit better. However, these are the entry model in the IE series and you would expect a weakness somewhere, otherwise Sennheiser may as well not bother manufacturing the IE7 or IE8 (which I would love to get my hands on at some point). Final Thoughts I have listened to them for approximately 800 hours now, and I still genuinely believe that these IEM's get better with every listen (albeit not as much of an improvement as before). My only concern, apart from the slightly lacking treble, was that the black plastic on the edge of the earbuds had begun to fall off. This black plastic has nothing to do with the main housing of the headphones, and is purely there to make the headphones look a bit nicer. Still, rather than pull it off, I decided to glue them back on with some rubber solution, as Araldite didn't seem to do the job, they now look as good as new. I would thoroughly recommend these headphones to anyone who wants a pair of headphones that deliver superb sound, but won't take up too much space. However, if you don't listen to music through headphones very often, it may take a while before you hear the true audio quality these IEM's can offer, as they do take a long time to burn in (around 100-200 hours). I have seen a lot of negative reviews about these headphones, but I firmly believe that these are due to the fact that they have been reviewed straight out of the box, rather than after 100 hours of use. These headphones are worth every penny I paid for them, and leave me intrigued as to how the IE8's can offer a better sound (other than the improved treble).