On power up do ⌘ Cmd+⌥ Option+O+F should go into the open firmware options screen. Try that. Other than that I know it's built into the open firmware and might be something you cant edit out.
Thanks! I will try it the next time i switch it on!
If you have an Apple keyboard there is a 'mute' key in the top row you can push during startup (I'm not sure what the equivalent would be on a standard keyboard).
I have a BT Apple keyboard but the BT takes a while to become available when i switch it on. Too long to push the mute key in time. Also what happens if i forget? So i sit down to use my Amiga, push the power button, then *Apple sound*. My nostaglia is all gone. Just. Gone.
Is it possible to remove that crappy little speaker?