Pros: Excellent overall audio quality for it's price! Excellent comfort for a pair of on-ear canes
Cons: Artificial sounding upper mids & highs. Builds are mostly plastic.
Without any introduction, here I will start:
Comfort: I wear glasses & I have no problem wearing these! It does get warm after sometime. Clamping force are not too strong.
Isolation: Isolates plenty of outside noise.
Build quality: Mostly plastic.
Sound: HEH HEH! Best on-ear headphone I ever tried. Lows are punchy & well controlled. Better control than HD439 at the same price. Satisfy basshead but it is not as strong as UE6000. Mids are very detailed & smooth sounding. Never did I aspect such excellent details from it. Mids are it's strong point. Really good. Upper mids & highs are however it's downside. Specially for treble/vocals fans as it sound artifical but that's the one and only weak point in sound. Details are excellent. Soundstage are good for a closed pair of on-ear headphones.
I would say, these are one of the best on-ear headphone. It is great for Electronics music or any songs without vocals as I find it somewhat annoying on these. Just my 2cents
FYI, I dislike too much bass(IMO, I find HD518 has too much), smooth & detailed mids & clear highs. Great soundstage & details type of headphones. Just so you know what I mean by "detailed" "smooth" etc in this review
Comfort: I wear glasses & I have no problem wearing these! It does get warm after sometime. Clamping force are not too strong.
Isolation: Isolates plenty of outside noise.
Build quality: Mostly plastic.
Sound: HEH HEH! Best on-ear headphone I ever tried. Lows are punchy & well controlled. Better control than HD439 at the same price. Satisfy basshead but it is not as strong as UE6000. Mids are very detailed & smooth sounding. Never did I aspect such excellent details from it. Mids are it's strong point. Really good. Upper mids & highs are however it's downside. Specially for treble/vocals fans as it sound artifical but that's the one and only weak point in sound. Details are excellent. Soundstage are good for a closed pair of on-ear headphones.

I would say, these are one of the best on-ear headphone. It is great for Electronics music or any songs without vocals as I find it somewhat annoying on these. Just my 2cents

FYI, I dislike too much bass(IMO, I find HD518 has too much), smooth & detailed mids & clear highs. Great soundstage & details type of headphones. Just so you know what I mean by "detailed" "smooth" etc in this review



As for HD439 vs UE4000:
HD439 is a full-size circumference while UE4k is a full-size supra.
HD439 bass are less controlled while
HD439 mids are warm while UE4K sound smooth and highly detailed xD
HD439 highs is a bit dark while UE4K's sound artificial as in "fake"
Sorry didn't get to try those S500 but the SL300 is bad in my opinion!
Billson :)
HD439 soundstage are wider but UE4K offers better clarity and detail :)