The Electronics Package

Special thanks to Calvin at the DIY Audio Forum for sharing his experience using inexpensive 230v/6v power toroids in ESL's.  They sound fantastic at about one-tenth the price of the specialized ESL toroids from Plitron or Aplimo.

Update 9/4/13: 

Finding suitable tranformers at a decent price is usually a problem in the US, where 230 volt toroids are generally not available.    

These 230V/6V  European toroids are my first choice and the price is unbeatable too.    

I would ALWAYS choose a transformer with a single 230 volt winding over one having two 115 volt windings because I think they are more robust.  That said, these 2x115V/2x6V toroids are available fast from Mouser in the US and they sound very good:   
Triad Magnetics VTP12-4170  

Update 1/10/14: 
Yet another transformer option would be a quad setup of these Antek AN206's, wired as shown in the schematic below.  Although I have not personally tested them, I see no reason why these transformers would not work fine and they are readily available in the US.   

Transformers & DC Bias Supply: 

The schematics below are color coded for the transformers shown.  If using different brand transformers, follow the phasing dots and make sure the (+) phase output goes to the rear stator.  This will ensure the woofer will be in phase with the panel.  Even then, you should verify the woofer/panel phasing as described here.  

Schematic with preferred VTX transformers:

Schematic with Triad transformers:  

Bias supply wired for 230 volt input:  

Left: The original electronics package, which I'm still using, is a tandem of Farnell 50VA 230v/2x6v toroids.