You've amassed a collection of digital music on your laptop, but your speaker system isn't capable of higher-volume listening. An alternative to purchasing dedicated external computer speakers is to plug your laptop into an existing stereo system or musical instrument amp. Mobile DJs, karaoke hosts, musicians and home recording studios use amplifiers to enhance laptop sound, and all it takes is a commercially available connection cable.
Inspect the back of the stereo system amplifier or the front of the guitar amplifier to locate the audio input jack. Home stereo systems employ two RCA-type audio input jacks, while musical instrument amplifiers use a single 1/4-inch phone jack.
Purchase the proper cable type at your local electronic store. Be certain that the cable is of sufficient length and is not a speaker cable. Speaker cables are unshielded and will cause the audio signal to hum due to disruptive RF (radio frequency) noise.
Turn off the volume control of the amplifier and laptop.
Insert the 1/8-inch stereo plug into the laptop's headphone jack. This is sometimes called a "line out" jack, and can be in various places on the machine depending on its manufacturer.
Insert the RCA plugs into the audio input jacks on the stereo system, or the single mono 1/4-inch phone plug into the instrument amplifier input.
Start the laptop's music program and turn the laptop volume up to approximately 1/3 volume.
Turn the amplifier volume up slightly until you begin to hear sound and adjust the volume accordingly. If using a stereo system amplifier, you may have to select the input source you've plugged into (tape, component, auxiliary) with the rotary switch at the front of the amplifier.
If distortion (fuzziness of sound) occurs, experiment with different volume adjustments of both the laptop and the amplifier until you cure the problem.
Do not connect the cable to the laptop's microphone or line-in jack, nor the amplifier's speaker or line-out jack. Damage to one or both devices may occur.