[der luda]

I am looking for such a cable,

Digital audio Koax Cable, SPDIF /on 3.5mm jack - RCA/Cinch

1..1.5m, high quality, unfortunately that doesn't seem to be common. Does anyone know a manufacturer?

thanks

 

[Roseval]

The only SPDIF over 3.5 known to me is the mini-Toslink but this is optical.
Care to be a bit more specific?
What gear does have a 3.5 electrical SPDIF out?

 

[der luda]

With the DAP players like the Ibasso 160, 300 the digitals coax cable is with the 3.5mm jack

https://www.oehlbach.com/de/anschlussarten/cinch/nf-113

 

[Roseval]

I see and to be honest I don't believe it to be SPDIF over coax (electrical)

https://ibasso.com/uploadfiles/download/DX160usermanuel.pdf

P 7:
It says the 3.5 is a line out/headphone out/Coaxial output port.
This suggest SPDIF over coax but it must be 3.5 TRS for the line out and headphone out to work
A TS as the Oehlbach will cause a shortcut, don't do it.

P8:

Coaxial Output Port: Use a mini optical cable to play music stored in the DX160 on an external device with a coaxial input port. Before using the coaxial output, make sure SPDIF is selected on the 3.5 interface.

Obvious, you need Toslink with a mini-Toslink.
This is the same as on older Mac's
The headphone out doubles a a Toslink out.