The VK-600se is something I don't have much experience with. From what (little) I know, it's similar to the Ayre in that it doesn't use any negative feedback (in the traditional sense). However, that's pretty much where the similarities stop I'd suspect. The BAT doesn't use a complimentary output stage, but is it class A design? I'm not sure I believe it is, or it slides into AB really early. Is it DC coupled? Traditionally, BAT power amps aren't (have to upcharge for fancy rebranded Jensen caps, right?).. not that these two things really matter in some senses, but perhaps you might care..