At a relatively low price you can enjoy really good sound with these headphones.
 
It is so popular for good reason, you could customise it to your personal taste, I just swapped out the cables to the Vmoda cable, and swapped the pads for Shure pads.
 
The FIIO E10K is not able to drive this headphones well.
The SMSL M3 and Grace Design M9xx is able to drive it well.
 
The sound is very balanced and neutral. Very pleasant headphones to use all day.

Another wonderful Massdrop exclusive. This headphones sound great amped (Schitt Stack and Grace Design M9xx)
 
The bass in this headphones is just.... a beautiful thing, not over the top but man... so... thick.
 
Treble and mids are good, thought the highs got a little hot at times.
 
The earpads were a bit too small for me, so a change to the ZMF omni sheepskin fixed that right up.
 
Comfort is great, the NON-removable cable is also really high quality.

Got this as a "replacement" for my K501s, has that same-ish AKG sound to it, comfortable all day listening headphones.
 
The earpads on these are superior to the old 501s, very big and comfortable.
 
Bass is a subdued, but its there in a very refined lowkey manner.
 
There is a big noticeable difference when this headphone is amped, a wonderful... addictive difference =)

Had this for more than 15 years, got a pair of 702s but the 501s were still my preferred.
 
Just an awesome headphone