@nightfall The VTL 2.5, 2.5i are single ended. The VTL 5.5 and 6.5 are both single ended & Balanced. Not often you will find a preamp that is balanced only, ecept for some of the ARC models.
As far as age of VTL's, most people say they are built like tanks + we forget that most gear is built to last many decades. The good stuff anyway.
I swear I'm not a VTL dealer, I'm pumping their tires plenty.:)