No idea, but it helped me figure out the source of the problem. It matches up with the difference between the image on the Jobeky website for a product that works compared to the product they actually sent out.
Jobeky sent me out five X 6.35mm stereo headphone splitters.
Jobeky Splitters
Re: Jobeky Splitters
Conclusion
Tested and not working
Demonstration https://i.imgur.com/T3WXqr3.gifv
PRO SIGNAL PSG00145
£5.49 + postage: 6.35mm (1/4") Stereo Jack Male to 2x Female Lead, Black
https://jobekydrums.co.uk/product/6-35- ... -splitter/
Tested and working
Demonstration https://i.imgur.com/XycJkSu.gifv
PRO SIGNAL PSG03432
£1.82 including postage: 6.35mm (1/4") Stereo Jack Plug to 2x Mono Jack Sockets Leads, Black
https://cpc.farnell.com/pro-signal/psg0 ... aMfpn=true
Tested and not working
Demonstration https://i.imgur.com/T3WXqr3.gifv
PRO SIGNAL PSG00145
£5.49 + postage: 6.35mm (1/4") Stereo Jack Male to 2x Female Lead, Black
https://jobekydrums.co.uk/product/6-35- ... -splitter/
Tested and working
Demonstration https://i.imgur.com/XycJkSu.gifv
PRO SIGNAL PSG03432
£1.82 including postage: 6.35mm (1/4") Stereo Jack Plug to 2x Mono Jack Sockets Leads, Black
https://cpc.farnell.com/pro-signal/psg0 ... aMfpn=true