I'm trying to use the nokia headphones button in my apps. Button pressed signal is emitted only when "jack bias" is on, so my aim is to set it on at app startup and disable it at app closing. I'm able to unmute it with alsamixer, but i'm not with amixer.

The command I use is:
amixer -qc0 cset iface=MIXER,name='Jack Bias Switch' unmute
but it doesn't activate it.