HEDD D1 wireless (Qudelix 5k)
The HEDD D1 is well suited to be used with a Qudelix 5k to turn it into a wireless headphone since it is easy to drive.
For people who may ask for the "Why?": It is very convenient. Try it. Once you are used to it you don't want to go back to a normal wired connection. You can move around the house. You can just grab it and go to a calm room if you want to listen for some music, when your usual listening place is occupied.
What is needed: Obviously a Quedlix 5k or sthg. similar (as I recall Fiio has some bluetooth adapter as well?). I use two 3.5mm 90 degree adapter for the connection on the headphones itself, that is nice but not needed. The stock cable would work but I had a Hifiman cable lying around which is shorter and uses an angled plug which is more convenient. Crucial are: A headbandcover with a zip from Aliexpress. And a strap, could be capra strap or some DIY-solution.
After attaching the strap, I took off the stock foam of the headband (with the plastic piece to keep it reversibel). This looks not well so I used the headbandcover. And realized that this can be used to store the cable in it as well and attach the Q5k on it. Not great looking but simple and reversibel.
Just ask if you have any questions.