So last night had the bright idea of connecting the external HDD that holds my music to the PS3 and plugging straight into the stereo from there (component cable to aux in on an old 70s amp). When the disk spins up I can hear it through the stereo, comes through quite loud and there is constant background noise as well. What can I do to stop this?

HDD, Stereo and PS3 plugged into same extension lead and within a metre radius of each other and the extension lead, if that makes any difference.

Sounds like a cheap extension lead. Usually from something not being grounded correctly, my guess would be the extension lead.

You can get a ground loop isolator which may solve the problem.

I’d agree with the above.

Used to get this a lot with poorly grounded laptop power supplies. Sometimes a noise filter would fix it and other times a new power supply would do it.

Off to Maplins at lunch then, thanks chaps.