I've had my CK10's since October and love them more every day. A couple tips I haven't seen posted here, just thought I'd add from my experience.
Tips - Comply Foam T-200's fit perfectly. The CK10 aren't listed on Comply's website, and if you ask them they'll tell you that they don't have tips that fit, but the T-200's work great. They don't fall off and go on with just the right amount of force. They're long enough to go in and seal properly without getting bunched up (unless you have tiny tiny ears). I'm a huge fan of foam tips for comfort and isolation, and foam tips on the CK10 really make them come alive. I spent the first week with the CK10 with just the stock tips and wasn't impressed, they sounded too flat and hollow. Adding the foam tips really helped them sound like they should.
Amp - I listen to them almost exclusively on my iPhone 4. Early on I found them a little too flat so I got a E3 amp and wow did that make a difference. They really came alive after that. Later I switched to a E5 with a dock port line out and while the bass isn't as strong as the E3, its much more balanced. I have my phone on the EQ off, I haven't found a need for it, and I'd rather not have the software messing with the levels anyway. On my desktop I have a Sound Blaster X-Fi HD 5.1 USB and find I don't need an amp at all with it.
Previous IEMs I've owned/still own are HJE900 (still own), TripleFi 10 (returned) and Shure E3c (Dog ate & destroyed after 2 years). The CK10 are the absolute best, though they require some tweaking to get there via tips & amplification.