[Anthrax]

my brother needs a volume control for his headphones from the output of his soundcard.

can we just wire up a pot for this ? what would the value be ?

 

[blueworm]

Yes you can just wire a pot.
Any value between 10K and 50K should be fine, but make sure it is a dual gang pot(6 pins ).

 

[DaKi][er]

10-50K would be for a high impedance amplifier input, driving headphones directly off a soundcard is comparativly a low impedance load so they will not work here

i don't know the proper way to have inline volume control, i've never had the reason to do so