Style tip: use .dbamp for audio amplitudes

Besides @nathan and @scztt’s good points – an extra benefit to using dB values instead of amplitude is that mixing (and linear interpolation/animation) works very simply when using dB (only converting to amplitude if/when needed, as a final step). If you’re using patterns (playing anything that uses Event.default), you don’t even need to convert to \amp, you can just set the Event’s \db key instead!