ebrobston

Thanks stormstudios, but it turns out it was a ground loop. I plugged one of the amps into one of those 3-prong adapters to lift the ground, and now there's no problem. Kind of surprised since everything was plugged into one power strip.

I forgot to mention - the noise comes out of both amps. A loud hum.

I've been using my HD500X as basically a multifx into a Vox AC15 and love it, so I got a second AC15 to run it in stereo. However, I'm getting a ton of noise when I plug in the second amp. Even if the second amp is powered off. Even if I don't have the guitar plugged in. Both amps and the HD500X are plugged into the same power strip, which is plugged into a power conditioner. I tried it with a different amp as the second amp, and still noise. I have the 1/4" out set to "amp". Help!

I'm having the same problem, and I followed all the instructions. I feel like it's 1988 again, and I'm trying to install an MS DOS application. I keep uninstalling and reinstalling, but keep getting the same result (or lack thereof).