Marly, the only way to go faster is to lower the nose and trade off the altitude for airspeed. Bigger loss of altitude = bigger rate of descent.
True, but only above speeds above min pwr speed. Below that, the faster you go in auto, the lower your RoD.
And anyway, how can you go faster if you are staying below min power speed?
On the power / airspeed curve, you have to replace the "power" curve with "altitude". At a certain speed, the loss of altitude is minimised. Go slower, you sink faster. Go faster, you sink faster, but get a bit more range.