This is my pair of AKG k240 MkII. I posted about it 9 months ago here: https://lemmy.blahaj.zone/post/7345872 Since then I grew tired of the original braid and made a new one.
I also wanted to go wireless so I bought the FiiO BTR5 dac/amp which has bluetooth. There's lot's of cheaper BT receivers online but since they are typically advertised for usage in cars I worry about their latency; I do video work so I need low latency to synchronize sound effects, lip sync etc.
I've only ever had bad experiences with BT audio on Linux so I'm pleased to say the BTR5 works almost flawlessly. No issues with pairing or automatically choosing low quality HFP audio (I'm using LDAC; supposedly the BTR5 supports AptX-LL but I'm not seeing the option to enable it, maybe my BT adapter, TP-Link UB500, does not support it, I don't know)
Range is not as good as some other BT headphones I've tried, after a few meters it starts to occasionally cut out. Still far more convenient than cable.
The cable is a bit too long (30cm) but it was the shortest one I could find. I don't know how to make custom cables.
For the price of all of this I probably could've bought better headphones but these purchases were made a few years apart. Plus I kind of like how janky it is, makes it feel homemade even though its all mass produced :)
Fiio had some misses early on; the E10 leaps to mind. But damn, they really turned things around. It almost feels like Fiio has the audio Midas touch, and now we're stuck with decision paralysis on which features and nuance we want. ๐