The headphone side is wire for a balanced connection but for some reason the cable they provided combines the ground into a standard TRS.

I used the existing jack to find the pin out then unsoldered it and fit a 3.5mm jack in. With the jack I used I had to enlarge the hole the cable goes in a little. I used epoxy putty to fix the jack in place. On mine both of the red cables are ground. Here are a few pics.

I got the new jack installed and it works great. Here are the pic with it in progress. I still need to paint the putty black.

It has been a little while since I messed with these headphones but today I removed the circuit board and replaced it with a 3.5mm jack. I still need to do a little work on it but I'll add some pictures in case anyone was interested. I tested it with the vmoda mic and it works great.

In the next few weeks I plan on replacing the cables and adding an integrated microphone jack. I'll add pictures when that is done. Now I just need to find out if the circuit board is actually needed or if it just holding the connector.

Yes you would need to remove the 4 tiny screws that are shown in the picture.

The one I received fits very well, and has not fallen out of my headset, but if the cable gets caught on something, or pulled on hard it will come out. My first thought was to take the factory cable, cut off the end that goes into the headset and attach a 3.5mm stereo female plug to it, but...

I found an adapter on ebay that fits perfect once you remove the locking ring.  Here is the ebay link, and a picture of the adapter.  I just got it in from china but is an exact fit. it is a 3.5mm stereo female to 2.5mm male 4 pole adapter. Ignore the velcro in the pic, that is for my labtec mic...

Glad i could be some help. Also i forgot to mention that if anyone recables and uses a 4 pole connecton, like the one that was originally used, make sure that the last two connections (the last ring and sleve)are the ground. I dont want anyone shorting out their headset.

I don't have any right now, but I will take some and post them here tomorrow.   I decided to go ahead and take some pictures of it. I am planning on using this for a gaming headset so there is a mic attached to the side of it.  If the pictures are too big let me know and I will resize them...

Tonight I ended up testing out what I though, and it worked.  I had a TRS 2.5mm cable so I opened the headphones up and unscrewed the locking ring.  Once it is removed I was able to slide the 2.5mm cable into place, then tested it again with the multi-meter to make sure that the left, right, and...

First off let me say I did search the forum and was unable to find an answer to my question. I picked up a pair of HD558s that I plan on using for gaming. I need a 1/8" stereo jack on them, and really don't like using the adapter. I know I can cut the plug off of the stock cable, but don't want...