How to pair an ampifier with an electrostat energizer/transformer?

So, I am a whole lotta confused regarding electrostats. I’ll try to make this simple and straightforward

So, I believe I own what you would call an electrostatic headphone energizer/transformator. This device does not have any knob or anything of that kind, only a power switch on the front. It has a Bias voltage of 580V, maximum output voltage of 600V RMS, impedance of 100 Ohms at 20Hz. Now, this device only consists of two large step up transformers inside, on the front you can plug Stax 5-pin Pro Bias, or two 3-pin XLR’s. It has a maximum input voltage of 12V RMS.

Now… all these specifications are quite alien to me, I am not sure what I am supposed to be looking at to be quite honest. And what exactly does 12V RMS mean?

I understand that this “energizer” cannot power the headphones on its own, it needs an amplifier. But, what exact specification should I be looking at when considering an amp? I am assuming that I will need a speaker amplifier, but how do I know it is compatible and delivering the correct amount of power to the energizer?
I was told that 12V RMS is an important specification, but I couldn’t find the output power on nay amplifier that was in volts, RMS is usually in watts on speaker amps… So, what am I supposed to be reading and paying close attention to? Does output power from a speaker amp matter, if so, what output power will/will not work?

I am assuming I need an integrated amplifier correct? But, I also saw one user used a pre-amp too, why is this?

From my understanding, on my hand I have a device that works on the same principle as Mjölnir Audio SRD-7 or iFi Audio Pro iESL (except iFi has two knobs), more or less much more similar to SRD-7.