Plug adapter with a resistor inside to increase impedance. I've used 75 & 100 Ohm adapters abs enjoyed the results.
Oh I see. Got it. I made one with 20 ohms resistor, and I also have the old Hifimediy USB DAC with 200 ohms output impedance. Or use the Geek Out Line Out which I think around 47 ohms. I will give it a try. Thanks!