Rubbish sound from headphone jack on laptop - how to fix?

Question

It's an oldish Dell laptop. If I could plug it into the stereo and listen to internet radio without it going gzzz upupup KCHHHH gzzz all the time, I would, but I can't.

Also have a less oldish Dell laptop, which is similar, less horrible but still poor.

The sound happens regardless of PC volume settings and whether any sound is being played at all. The mere act of plugging in the jack seems to create the buzz.

Answer 1

The headphone Jack has outputs designed to power headphones ONLY. whereas inputs on Hi Fi are designed for +/- 1v high impedance signals ONLY, the reason it sounds bad is you are overloading the input its like putting mains into a car stereo.

you need a dedicated Audio output device and these are often USB based and example is the USB Avid m-audio M-transit USB which gives all of the following:
Audio Input Line
Audio Input Mic
Audio Input Optical

Audio Output Optical
Audio Output Line analog
Audio Output Line Digital
Audio Output Headphones

if you want decent sound use the correct output/input combination

Answer 2

It could be radio-frequency interference from the processor leaking in to the sound system. Do the sounds co-incide with when you give the computer a task (eg. move the mouse, load something from the harddisk).
If they do then there is probably not much you can do.

Answer 3

a new sound card may help