I have owned these for about 3 years, during which they were replaced twice because the cables snapped (a well known problem for these earphones)  I use them with a sony mp3 player and with the black foam tips. They isolate outside noise very well using these tips. 
 
Now onto the sound signature. These earphones really emphasise the mid range of the sound spectrum, meaning the mids are much more prominant than the highs and the lows. Using a rock song for an example, this results in guitars and vocals sounding more prominant than the drums and bass. 
 
What this type of sound signature does for songs is very nice. To me me most of the emotion of a song is in the guitars and vocals, so having that closer to you than the drums and bass makes u really "feel" the song and make it more engaging.
 
As an experiment i eq'd up the bass and treble a bit, to bring forward the bass and drums to the same level as vocals and guitars. It sounded even better at first, but after time i found myself not really paying much attention to whats playing. I realised that when the vocals and guitars louder than the rest of the instruments, the song really pulls u in and grabs ur attention. 
 
So i will say this, If you like to give your full attention to a song and really 'be in it', then this is the earphone you want. But if you prefere just having your music playing in the "background" while u get on with somthing else, then these will probably irritate you a bit, as they are very 'closed in' your head, rather than 'open' sounding. If you prefere a more open sound, you would need the mids of these to be pushed back a bit, to the same level as the lows and highs. 
 
Sound quality is excellent, with all instruments sounding crisp and tight.