I did it! I used the smallest 2.5 jack sockets I could find, 30 cents a piece. Nothing got damaged in the process (not even the old MMCX connectors), no drilling, gluing was necessary, I just removed the old connectors, soldered the new ones and that's it. The mod is fully reversible. Took me a little over one hour.
Fixed cable would be even easier to do, but I like the idea of detachable cable, just not one that makes the headphones useless :)
Plus, I already have a few cables terminated with 2.5 mono jacks for Sennheiser HD700s.
And now I can use the Onkyos without them disconnecting all the time, hell, I can headbang with them on! And if the cable goes bad, I can make a new good one for about $10, or buy a cheap cable (like the one in pics below) for even less.
If you want to have a look at a step-by-step guide with photos, it's here for now:
And a few pics:
Here's the end result. Now I need to make a nice white or at least silver cable :)
And BOOM BIDDY BYE-BYE ridiculous Onkyo cable and connectors!
Edited by rlisin - 3/8/17 at 6:41pm