Hi,
 
I just recently bought a AKG K92 headphone for my computer. Before them I used the KOSS UR-40.
Seeing that there is a big price difference (and from what I had read) the AKG-K92 would be a far superior headphone.
However when I tried it with Spotify the sounds were sharp but lacked depth and bass (sounded muffled). I tried same songs with my KOSS UR-40 and the sound was much more rich and with fuller bass (very little bass with the AKG-K92) and not at all as muffled. I am not sure why this is, as the AKG's are supposed to be really good headphones value-wise and from what I thought better than the KOSS UR-40 that are half the price.
 
I plugged them into my X-Fi soundcard and there still is a very noticeable difference between both of them. The AKG does sound better when I press the headphones really tight against the ears. Without the earpads the sound seems to get worse. The bass of the KOSS-UR40 is way more deep than the AKG's. Pretty dissapointed so far. 
The constants do sound a bit more clear on the AKG but the overall sounds is muffled and the bass is really lacking. The KOSS has an overall much more complete sound spectral it seems to me.

I tried both headphones with a CD-player instead and same song as with Spotify. The AKG headphones clearly came out the winner. 
I believe one or many of following factors may have been in play:
 
- My ears have grown accustomed to overly-bassy sounds
 
- The impedance match is better between the AKGs and the CD player than with my computer's soundcard. I guess this explains why the volume is lower on the AKGs when I switch between them.
 
- The AKGs need to be used for a while so that membranes become more flexible. The KOSS have been used a lot already.
 
- The bitrate of the music really brings forward the nice balanced sound of the AKGs compared to the KOSS.
 
Over all I'm satisfied with the AKGs now. 
 
Could a mini-amp connected inbetween the soundcard (X-fi Gamer) and the headphones (200mW,32Ohm) perhaps make the sound even better?

An update on the situation. I flattened the ear-pads a bit and now there's a huge difference. These headphones a really sensitive about closing in the sound, else they wont sound nearly as could as they can. Just to give you an example of how sensitive it is; if you are wearing glasses (thin ones) that's enough to make earpads not sealed enough and makes the sound worse. It is a good thing the earpads are detachable and can be change easily, softer ones will surely take care of this.