| I just heard Edgar play a few weeks ago and when asked about his tuning, he explained that it is, from top to bottom, A, E, B and E/C (depending on whether or not his extension is open. The point is, he basically uses solo tuning except for the bottom string, which is tuned to standard orchestra pitch.
I'm guessing he couldn't find a long solo extension string and got used to playing that way. Thomastik is rumoured to actually make a long F# (or extension D) but I have yet to actually see one in person. I tried ordering one for quite some time several years back, but finally gave up trying. | 
