First Watt: current vs voltage

Hi All,

I'm interested in giving First Watt a try. I have Audio Note AN-E speakers, which are efficient, I like SET sound, and I'm intrigued by the approach of First Watt.

However, in man places I read that First Watt are current amps (in opposed to voltage amps) and thus they can only be used with single drivers speakers.

Is this the case for all of them?

Is there a model that will work well with my AN-E?

Thanks,
Walfredo