I would first un-solder the wires from the jack and confirm with the
meter (on resistance) to confirm that you have the pairs correct.
You should be able to identify the left and right pairs as well.
You can hear a pop or rustle caused by the voltage from the
meter. The meter should indicate the rough impedance of
the headphone driver.
Then you can re-solder the wires to the jack again.
Tip = Left
Ring = Right
Sleeve = Return
If you can not identify the...
Yes, indeed. You just have to observe the minimum input voltage requirements.It would run quite nicely off 12 volt vehicle power. For DC, anywhere between9 vdc and 12vdc would work great. Just don't exceed the working voltage of theinput cap which is 16vdc in the BOM.