audio output and input

[pol]

Audio output, as i listen music using juk or amarok, occurs both through the
laptop speakers and through the headset plugged in. I would expect sound to
be channeled only to the headset. What is wrong?   

Here is my system setting:
 Sound System
  'enable sound'  is on
  the audio device is set as 'Autodetect'

Alsa and Arts have been installed.

Moreover, recordings through the built-in microphone is very low volume.
Is there a way to tune my audio set up?

thank you 

Pol