bought 15 days ago. phones are just warming up. 
 
Bass is awesome... 
 
Almost one year its been.. Already burned in. Now SE215 is my daily driver.
 
Signature feature is its BASS. its refined and almost perfect. wouldn't distort much, except if you amplify bass. You aint need amplification for this babes. has its own bass, thats awesome enough for me.
 
Next thing is it's Mid. its very pronounced, impressively. its not annoying at all. compared to my audio technica, this shows off very clear and pronounced mid without annoying me. 
 
Treble is what I am disappointed about. I cant hear 10k or 16k (Hz) at all. very low 8k is there. 2k and 4k is pronounced like the mid. so the mid-high sounds will be like pretty loud. There might someone who dont like that. but i dont mind. i like the sound of lead/distortion/treble guitars. (rockhead) 
 
I dont like the way it exhibit Metal, Rock songs. Alternatives are OK.
Perfect (according to me) for POP, HIP HOP, EDM, and other bass heavy songs 
 
Very impressive soundstage for the price. its not perfect, but you can somewhat distinguish instruments. i hear more sounds than my audiotechnica.
 
design is good, but its made out of plastic. the wire is sturdy. sits perfectly on my ear. 
personally, I cant use it continuously like my audio technica, after about 1 or 2 hours I give up, coz of fatigue and a slight pain. 
 
ISOLATION is the best for the price. i can hear nothing while the music is on (with the foam)
 
All the stars for its value... X) 

I love classic and rock music. And actually my kinds of music works really better through these. Each time I listen to music, I can feel the soul of the music. Honestly I used a SoundMagic ES18 budget pairs for 3 years I assume. And they worn out, one speaker is dead, unfortunately. Then I bought these and a pair of Audio Technica ATH PRO500MKII hoping for better bass. What I got from these DJ beasts is annoyingly recessed mids. I really spent some work with different DACs to get better bass and reduced mids. Trust me, the thing went BOOMBLASTIC. #selfie by chainsmokers, really made me stunned. 
Ok, lets come back to WS55. Compared to PRO500MKII, this has an amazingly well balanced sound. 
Its bass is solid, clear and 'non-annoying'. It pronounces middles of bass (10-60Hz) without any clutters. 
I hate mids being recessed, and I blame PRO500MKII for that. With these, I can't say it annoys me at all. Balanced with trebles, sounds that are bound to mids are clearly heard, without making it recessed.
Treble is impressively crisp. 
One word : The Beats by Dr Dre are nowhere near this legend.
 
The clamp is what make me sad. The 90 degree swivel is good, but not that much, if it keeps making that weird noise. Looks like it needs a lubricant. Plastic to plastic friction. It's dominant when listening to music too. 
The cans really cause pain. It's a design flaw. I'm really depressed with that too. But if I adjust it to some comfortable position, it doesn't pain at all. I used it almost 3hrs straight. I wont usually go that long. 
I never distressed by its clamping force. 
and by my rating, I am not evidently comparing this with anything far more superior than it's class, like senny HD800 or else!  
I know it's not made for noise reduction, But i'm disappointed. Neverthless, it slightly reduces noise, but not in a bus or in a flight.
 
If your light bulb is lit because of my review, I'm extremely grateful. Or If you find anything wrong in these, I'm extremely sorry. Do correct me.
 
i gave it 5 stars because i love its soundstage. 
i gave comfort full rating coz i use custom pad.