Tonight a friend of mine slided his empeg in his car sled, and powered it up. We both started to hear a quite loud ground noise we had never heard before. The noise is constant, and seems to change slightly, somehow, when skipping to the next song. It also seems to amplify the hdd noise.

This happens with his empeg only, both in his and in my car. It also happens at home, when the empeg is plugged and is in AC mode.

At home, he usually uses a 12V 1A adapter. However, if he uses a 13.8V 3A adapter, the ground noise disappears.

We need help to sort this out. What can my friend do to solve this? Any idea on what may have caused the ground noise to appear only now?

Thank you all in advance.

A loose wire, maybe?

And although I'm sure you've seen it already, there's a bunch of useful links about ground loops in the FAQ here.

[thinking] But then why would the noise be there also at home (therefore using the two rca connectors)? Mmmmmm.... [/thinking]

As to the ground loops in the car, I am quite sure it is not that problem since the ground noise has just appeared in both my and his car (completely different installs), and at home, and only occurs with his empeg and not mine, so this makes me think it's something inside his empeg...

But then why would the noise be there also at home (therefore using the two rca connectors)? Mmmmmm....

Sorry, didn't catch that part. If both the home and car noise started at the exact same time, then it could be something wrong inside the player, like a loose wire or a blown component.

Then again, you can get ground loops in home equipment, too. When I plugged my player into a certain friend's stereo with the Sunpower brick, I got ground loop noise. When I switched to the compact plug-top adapter, the noise went away.