HP Pavilion DV1000t Hardware And Software Manual page 91

Multimedia
When any device is connected to an audio-out jack, the internal
speakers are disabled.
When you connect a device to an audio-out jack, use only a
3.5-mm plug.
Setting Audio Output Preferences
The computer is set by default to transmit analog audio signals
through the 2 audio-out (headphone) jacks.
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