I just picked up a pair of Sennheiser MX365s decent enough sound quality to hear the imperfections in my iPhone radio stations at 192kb/s MP3s, ridiculously powerful enough with 110db of output full range from 20khz to 20000khz. Very cheap at $35. I will give some feedback with some decent quality encodings as below:
The things I'm noticing thus far is that they definitely do introduce some static noise of their own when you adjust the volume. This is not ideal in terms of speaker quality, but it's not too bad when music is actually playing. I guess the other thing is as with all Senns they are a little too cold and clinical which is nothing not to be expected from Germans and the industry which Senns are targeted towards. There is very little colouring, except for the casing of the buds themselves, but not in the actual audio, very flat. Not warm, not bright, a little clinical... enough clarity though to hear imperfections.
I like my speakers to be a little warm, these are definitely cold, they do however allow you to hear the full range of sound. Very clear mids and highs with enough bass but not enough to add any real colour. They are actually pretty airy for what they are which is nice, but more akin to a monitor sound than earphones most people would put up with for every day listening.
Not everyones taste by any means at all, but for the price and if you want to hear your music pretty close to how it was encoded then they are decent, of course when you factor in the price. You would listen to other cheap headphones that would mask the imperfections of music one way or another, these really don't which would proclaim some to say they're terrible earphones, but... I guess I've had the chance to listen to a range of pretty decent speakers, they're not terrible as such, just a little typical of Senns for a rather cold sound.
You will get annoyed at your music listening to these earphones but that will be with your poor quality encodings or the poor quality recording, not the earphones themselves. You will hear the artifacts in poorly encoded MP3s, you will here the compression in the recording, you will hear the pops and crackles on non-digitally recorded auidio definitely not for everyone but yeah... they're decent enough.