I have a Stax SRD-7 Mk1 electrostatic energizer in good+ condition for sale. The Mk1 is Standard bias only (not Pro bias) and has 6-pin jacks so you won't plug your Pro bias head phones in by mistake. If you have some of the classic Stax, this will be an appropriate energizer to allow you to connect your head phones to your favorite amplifier.

My unit has a standard 2-prong US power/ mains plug.

I've installed a 4-pin XLR on the signal cable which makes it easy to connect to different amps if you have a corresponding pig-tail.
Pin 1/ L+/ white
Pin 2/ L-/ green
Pin 3/R+ red
Pin 4/ R-/ black

I know my ad says shipping to the US only, but I can make arrangements to ship nearly anywhere using the US Postal Service. I'll bet international shipping will be expensive, though.