Well, I got my CX300's today (technically yesterday now) so I might as well weigh in also. First let me say, I HATE packaging that you have to destroy to get to the merchandise. Second, if Panasonic can give us a nice little bag with their $20 canalphones, you'd think the Sennheiser could throw in a little something for storage with their $70 canalphones (I'm glad I only had to pay $40). And now, let me say that all is forgiven.
These sound absolutely amazing. When I first put them on I thought there was a slight veil and that the bass dominated the music (although it wasn't boomy). So I let them burn in for about 4 hrs will I ate dinner, watched a little TV, put the kids to bed and hung out with the wife for a while. When I got back to them I could tell that they had opened a bit. So I decided to put them through their paces with some of my usual reference material. All listening was done on my PC rig.
First, The Killers - "Hot Fuss". This CD has some great sound and can be quite bright on some phones. The CX300's handled it with ease. Bass was awesome but never boomy. Mids and highs were clear and balanced without any sibilance or harshness. Vocals were very distinct, again without any harshness. Ok, these do rock very well.
Next, Shpongle - "Tales of the Inexpressible". This is one of my all time favorite Cd's and honestly it can actually make bad headphones sound better that they are. But on good headphones it is a true joy to listen to. The music has many layers, deep, thumping bass, great electronic beats, guitars, female vocals, as well as a lot of ambient sounds. Again, the CX300's were spectacular. The bass almost rattled my teeth and yet remained detailed. The main beats were crisp and fast. Guitars and vocals soared. And I heard ambient sounds that I never had before.
Last, Steve Tibbets - "YR". For those not familiar, this is, IMHO, one of the greatest instrumental guitar albums ever made. Again, many layers to the music even though it is almost exclusively guitar and percussion. The songs merge electric, acoustic and bass guitars with a wide variety of different percussions including kalimba, congas, tabla, bongos and bells. This is another of my all time favorite CD's and I have listened to innumerable times over the past 18 yrs. And all I can say is WOW! Again, the CX300's reproduce every sound perfectly with amazing detail.
Along the way I compared the CX300's to my RP-HJE50's (my first and only other foray into canalphones). I was never able to get a great seal with the Panny's and wondered if that would be indicative of all canalphones. The answer is definitely NO. The Senns fit great and are more comfortable. They also beat the snot out of the Panny's in every area of sound. The Senn's bass is in a whole other league and while the Panny's have better extension on the high end, it is harsh and fatiguing. No comparison.
While bass certainly seems to be the strength of the CX300, I cannot find a weakness. These are smooth, silky and lush but not at the expense of being able to rock when they need to. I always thought I liked my headphones a little brighter but I think I had just never heard highs done right before. Overall, I still prefer my HD590's, as they do everything the CX300's do but taken to another level of refinement. But I think the CX300's may have just moved into 2nd place. I will have to listen to these for a while but I think I may end up preferring them even to my SR80's. While the SR80's sound great, they can be quite fatiguing. The CX300's are just smoother and more refined. Of course, those aren't words normally associated with the lower end Grado's and for that very reason, if you're a Grado fan these may not be your cup of tea.
