Pros Many customizable in-ear tips, incl. Comply foam ear-tips.
Truly powerful low frequency notes one can feel.
Lower-priced than headphones of comparable quality.
Built-in volume control, song control, and microphone in ear-buds.
Cons Large for in-ear headphones.
Audio is bass-centered: "Too much of a good thing."
Summary The only reason these aren't getting more than 4 stars from me, is because I'm certain there are better headphones out there, if you have the money to dish out on them.
These headphones provide something that I have yet to experience in another pair of headphones. They provide a strong amount of bass, that carries a substantial amount of air pressure (best demonstrated while "listening" to low frequencies of 5-15Hz). A friend of mine, a true audiophile, has had both a pair of Beats Pro by Dre, and a pair of fairly high-end Klipsch that I can't recall the model of, which I borrowed and listened to the same track on each of the three and found that the AH-C300 held their own in audio fidelity, and provided more bass than either of the other pair. I had a pair for about four months, during which time they never left my side, and had a dedicated ipod classic used to store my music library that was carried along with them in the leather zipper pouch. The only reason I don't have them now is because I set them down for too long and someone stole them. A true loss for me that day. I have yet to find a pair of headphones to bring me that much enjoyment from my music.