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A perennial topic here has been USB noise on iPads and other devices when they get into a ground fault loop when using the USB Camera Connection and feeding the audio back into whatever is being used to control the iPad. (In my case, a Yamaha CP40.)

I tried a couple things, with no luck. This week I bought a Kensington Noise-reducing AUX Audio Cable to use in the car. I did not intend to use it with the iPad/DP setup because I didn't think it would do any good, but on a whim I plugged it in anyway.

It works perfectly. All the buzz is gone when the USB is plugged in. The audio sounds the same if I plug headphones directly into the iPad or the CP40 with the iPad fed into the AUX IN. Problem solved, at least for this particular situation.

Do you have any idea how this cable is different from any other cable?

. Charles

There's very little info on Kensington's page about how it works.

http://www.kensington.com/kensington/us/us/p/1409/K39203US/noise-reducing-aux-audio-cable.aspx

In all honesty, I only picked it up for cheap to see if I could get it to kill the screeching noise on my phone when I have it hooked up to the charger and the AUX jack in the car. Haven't even tried it in the car yet.

Earlier on the piano I tried a supposedly special shielded "audiophile" 3.5mm cable that did nothing.

As ground loop issues are normally not resolved by better cables, maybe it simply contains a ground loop isolator. Normally these isolators are more bulky, but it might just be a smaller SMD design.

Thomas