I have acquired 3 sample units of these AEC 4.4mm Pentaconn plugs, and am keeping one for myself. https://www.aecconnectors.com.tw/en/2-678-13334/product/AUDIO-PLUG-AP4-4-550-id226505.html Spoiler: Invoice photo The internals look pretty much the same as this one that cost $30 from OC Studio, but the barrel doesn't provide any additional strain relief screws. Schematic can be downloaded from here: https://www.superbestaudiofriends.org/index.php?threads/cable-building.86/page-42#post-315576 They cost the equivalent of $13 each, so I will send one to the first two people that provide proof of donation of $15 to SBAF (or if you want both, donate $30). I will cover shipping worldwide by standard int'l post w/o tracking. If you want fancier shipping, let me know and I'll price it out at your expense. I take no responsibility for any psychological damage caused during the soldering of wires to this connector.