Wolcott if you can find a pair. Excellent with Apogees. Manley Neo classic 500's or maybe their Neo 250's...might do a good job. Try to stay with tubes unless you absolutely can't find any that will work. I run Apogee Duetta Sigs (which are much much easier to drive) and run tubes exclusively (I'm actively bi-amping to get the best dynamics). SS can't do what tubes can and on Apogee ribbons it is pure bliss. Try the VTL's [carefully] and if they won't hold up, keep seeking tubes as much as you can.
Good luck and keep us informed.
Grant
Good luck and keep us informed.
Grant