That's his prototype amp where he does his part tweaks (Swaps in different output tube sockets or different output transformers etc) with my VT99 adapter provided to me by a good friend
You do not need partial silver transformers to run HD800s. You don't even need them to run K1000s, but they help in making the K1000s sound good as they are pretty demanding "headphones."
Reports from foo_me and Craig is that the partial silver takes the amp to a whole new level. Text message from foo_me while listening to it: "Omg...BA sounds so good with the partial silver transformers! No contest."
Craig in email: "I had not heard the silver outputs on the AD1 with the VT99 before, truly amazing, I seriously doubt there is a better headphone amp on the planet."
So I don't know if this is something that other BA owners might be interested in, but it seems like a solid upgrade for ~120 bucks (Last I heard anyways.. it could have gone up or down I'm not speaking for Craig with regards to cost
Jarmel the Balancing Act is the next up on the assemblers queue for Craig. There used to be some things in front of it like the Zana Deux SE/ZDT but I believe those are done and the BA is next. Unfortunately there are other larger standing orders (Apparently things like Vizio TVs) that can bump Craig's smaller orders down the queue... so it is somewhat variable when exactly the BAs will be assembled, but once they do start getting worked on he is confident they will be all done in 2 weeks though he will start shipping them as he gets them and they trickle out a few at a time rather then everyone has to wait the whole two weeks to get theirs. So here's to hoping they start this week or next
Jrisles your friend is right that it is not a "true" balanced amp in that its not 2x a single ended circuit. What Craig does with the balancing act is that he uses high quality transformers to balance single ended signal coming in and output going out. This is how the TTVJ 307A does balanced as well. I don't think anybody except for Singlepower and now maybe Woo Audio (I think the WA22 is true balanced.. not sure) offered 2x circuit balanced tube amps though frankly Singlepower didn't seem to really execute it well enough to handle the additional complexity of doubling the circuit as there were issues like single ended output would be ultra terrible though that might be attributed more to their horrible design/build quality.
Anyway in the end the BA sounds amazing single ended and it does sound better balanced. Craig was a balanced skeptic most of his life until very recently I think when jp11801 tricked him into making the Eddie Current HD2 which 909 now owns (Again transformer coupled and transformer balanced) and the improvement was enough to convert him. Thanks jp11801