Fox,
If you want othe electrostic sound without high voltage panels next to your head, you could try and track down some electret condenser headphones. Audio Technica used to make these, and we have a pair of ATH-9000. They come with a step up transformer, and you drive them with a power amp rather than a headphone amp, but there is no static voltage across the panels.
Might be worth considering if you want to try something different for headphone mixing. The ATH-9000 is very open and very precise to my ears. They don't harden up with volume - it's pretty easy to find yourself with them at high levels since they are basically effortless.
Cesare