LDR Active Preamp - does it exist?

You would want to use the ZStage between your source and the Lightspeed. If your source is 2V you can use the buffer to add another 2 or 3V to the signal. Then use the Lightspeed to attenuate.

The idea of such a device that adds voltage to the signal is not unheard of. We actually make one using all passive parts and it also has a built in attenuator.

The battery is not a significant improvement. There is a difference in the sound but I cannot precisely pinpoint what it is. I swap the power supplies around every so often, but could live with either one.