Oh, OK. So the page should say something like "-3dB is 50.1% of 100% power, 70.8% of 100% amplitude"? That makes sense.

The bandwidth in octaves quoted for the car-player hardware EQ -- assuming it's the same as the Karma software EQ -- is between the points where the gain in dB is half that at centre. So the example I gave upthread is still right AFAICT.

Peter