After searching on the internet, I found a nice option, the Superfux HD 681.
This headset got pretty good ratings and sound was especially good after applying the "mod".
What mod? I searched for a bit, and found this document:
HD681.pdf
It describes how to add a couple of filters to the headset, so the main downside (relatively harsh high notes) is taken care of. Seems easy enough to implement.
Next was to find a place where they sell the headset. I found that Conrad sells the headset for an acceptable EUR 19,99. Unfortunately it will be more expensive, because under EUR 25,00 you need to pay for shipping, which would get you to a total of EUR 26.94.
But they also sell electronic components. So I decided to add the parts you need to build the filters:
This adds up to a total of EUR 4,68 not enough to get to the 25 euro minimum. I just added a couple of more resistors and placed the order, essentially getting the parts for the filter for free :)
I recieved the headset after about a week (Conrad is a very slow web shop). It looks pretty ok:
It even comes with a carrying bag and a 3.5mm to 6.3mm jack adapter.
I used the parts to solder the filters together. In the picture below are both fiters for 1 side of the headphone.
I bent some of the components around and put some heatshrink around them to prevent unwanted contact.
With both filters inside the housing it is a bit more crowded but looks ok.
After changing the other side I tried to listen to a couple of different tracks, and you can clearly hear the change. Of course this thing is very personal, but I like the sound better with the less harsh high end.
The standard cable is quite long. It would be really handy if the headset had a detachable cord. I took the side of the headphone where the cord is connected apart again. The space available to put a connector in the housing is pretty small. After a bit of searching through all the connectors I had in stock I found a Neutrik connector that is pretty shallow.
A quick fitup looked promissing.
After removing some of the plastic with a file, fit again, remove plastic, fit etc. I got it to fit pretty good.
Now add some wires and solder the connector in.
And with everything closed up I'm pretty happy with how it looks.
The standard pads on the headset are plastic which can result in sweaty ears :) Lots of people replace the earpads with those from a AKG K240, K241, K242 or Denon D2000. I found a set on ebay. The cheapest I found was around 14 euro's which is pretty expensive compared to the price of the headset. Below is an image of the standard and new ones next to each other:
They do feel a lot better, and make the headset much more comfortable to wear.