Mines came equipped with #3 tips. I quickly began test fitting each set for the best comfort. What I found was that with the smallest tips, the CKM500s were able to fit deeper into the ear canal, and thus give a more powerful sound. Though this was the most comfortable for me, the bass was literally rocking my head haha. Almost in a way that there is too much bass. Though I like a lot of bass most of the time, I felt like the bass was kind of overpowering the mids. After switching to a size larger, the #2 tips, the bass had lessened, but the perfect fit had been slightly lost. I sort have a preference to deeper inserted IEMs, as I used my UE Superfi5 pros for a long time, with double flanged tips that would be inserted a bit deeper than the normal tip.
I've burned in the headphones for about 24+hrs now with and without listening. The sibilance has almost completely gone away now, and the bass has tightened up just a bit. I need to run some heavy snare drum music through them now, as I've mostly been playing heavy bass, or vocal tracks through them.
I'm using the CKM500s with my Sansa Clip Zip, ranging from 65 to 80% volume. I didn't rock box this Zip yet, as the last one I rockboxed installed mostly ok. But shortly after installation, the screen had a blue line of dead/frozen pixels going across, vertically. After that debacle I returned it after reformatting the thing, and got a new one. But haven't rock boxed it yet. I was thinking of getting a fiio E17 in the future, maybe when prices stabilize again. Do you guys think it would enhance the audio well, or would it only just add more volume control?