Sennheiser CX 175


New Head-Fier
Pros: price, isolation, louness, comfort, warm and good soundstage.
Cons: veiled
Build, look and comfort: These iems look very nice, has unique design. The earpieces seem built sturdily, the cable seems durable. These are so comfortable that you mayn't feel they're on your ears after wearing them for some times. I would appreciate flat cable like mh1c or xb series from Sony.
Sound: before burning in, there's a very noticeable hiss in the sound, around 16khz. Feels like breaking glass or something like that. 
After burning in, that hiss is gone. The sound is very warm now. Also, the sound is more veiled this time, before it used to be brighter and crispier. 
Overall sound quality is good. There is a soundstage, although, a bit unclear due to veil. It's due to warm sound signature. The frequencies seem balanced enough. There's a very good bass response. You may want to wear them around ears for better isolation and less microphonic noise. maybe These iems are very sensitive, goes loud enough at low volume. High volume could damage ears, beware of that.
Isolation: Outstanding isolation.
Conclusion: Excellent buy for price. 
Is the hiss noticeable even without music playing? If so, that's actually the source and not the earphone. Anything with high efficiency will reveal the source's noise.
No it's not. It's only noticeable when audio is played. However, the stock Sennheiser eartips has much less hiss than Sony silicon eartips. I thick you could just tune the equalizer a bit for the best sound. The frequencies around 16khz should be tuned down a bit.