Pros: Defined Bass. Punchy, very present, not overpowering. Great lows and mids. Clarity is amazing for its class. Amazing isolation.
Cons: Some of the highs can be distorted at times.
I first purchased these because I wanted something good to use. Everyday travelling to and from school/work would take me about 3 hours (round trip); so having good quality IEMs that isolated me from the noisy bus and other distractions was something I wanted to have. I saw these in-store and thought I might as well try them. I've heard of Sennheiser before but was the quality as good as its claimed? (mind you these were my first pair before I really got into audio/headphones etc).
I thought it might be important to state this.
I used my Cowon J3 with custom equalizers (found here on head-fi). No amp.
The music I listen to is pretty much anything;
Dance/Techno, Rock, Hip-Hop/Rap, Classical... I mean anything.
The low's were done very well.
The clarity was incredible. Comparing to the last pair I had, I could hear so much more that I didn't even know I was missing. For the price that I paid it already felt like it was worth the investment.
What impressed me the most was the bass. It was very punchy and defined but not overpowering. The bass was never muddled and it was always enough to be enjoyable and able to get me into the mood (of the song, whether it was upbeat or slow).
These, as far as I could it was just as good as the lows. Offering the same great clarity that I became so used too. The bass too was just as good as the lows, never leaving me disappointed or regretting my first 'expensive' IEM purchase.
The CX300II's highs almost as good as the mid's and low's. A few of the songs I listened too distorted very high notes. It was easy to deal with since it wasn't too often that I had a song that hit those highs. It could've been improved here but for the price I would live with it.
The first thing I thought when I was buying these was will they last long enough to be worth the money?
Simply put, yes!
While it looks flimsy, it was able to take some fairly decent blows from me. Almost a year and a half later they broke due to my carelessness. As long as you store it properly when not in use it should easily outlive the manufacturers 2 year warranty.
If you're looking for something that provides great bass with great quality without having to empty the bank these are great. These are a great starting point if you don't want to spend too much. I'd still be using them now if I could. Definitely a great buy for the price.