I've got an Emmeline "The Hornet" by Ray Samuels Audio amplifier. It has the option to run off a battery or with a 12VDC regulated power source. So far I've only used it with my battery-powered MP3 player, running on a 12V power supply.
Now I recently acquired an ODAC to play music from my PC. However, when I connect it to the amp there's a loud siren sound from the amp output! If I disconnect the 12V power supply and run the amp off battery, the siren noise goes away. Any idea what might be causing this?