Pros: Lots of bass but not too loose, midrange is articulate, treble isn't too recessed
Cons: Tight clamping force, flimsy cable, stiff earpads, sounds a bit congested overall
As the description above implies, it has lots of bass in its sound signature. The bass is of good quality I would say as it is very punchy and presents good impact. It is a bit loose in general, and when you’re playing audio tracks that require fast retrieval on the low end, the K518LE gets confused. But that’s not saying too much considering the price of this headphone.
The midrange is articulate. The bass doesn’t really overpower the mids but since it’s impactful and sometimes loose (even muddy), the mid-midrange going up to the upper mids sound a bit veiled (which is not recessed). Although I really didn’t have major problems listening to my modern day pop tracks nor some good old local music.
Treble is not as recessed as in K619 DJ however, it tends to be smoother in comparison. I recall that the lower treble of K619 sounds a bit artificial and it doesn’t seem to be the case with K518LE. Overall, the treble is not lacking heavily although a bit more sparkle would probably do it good.
As it is a small closed headphone, there's not much to expect in terms of layering and soundstage. The latter is smaller than other on-ear headphones that I have but it's not that big of a deal
Comfort-wise, it's not the most comfortable headphone due to tight clamping force. Headphone looks rugged but not indestructible. The cable is very stiff in my opinion and gets tangled rather easily. The newer K619 fixes most of these issues though.
Full review and pictures here: http://www.headphone.ph/akg-k518le-basshead-headphone/