Congratulations, Marty! What an inspiration!
Given that most of the commentary regarding the ST70 replacement boards comes out of the advertising for them, how do compare the sound of the stock and VTA driver boards?
Although I bought the VTA board before I even built my kit, I used the stock board to "baseline" things before moving to an upgrade. It turned out that once I put good (RCA) 7199s in mine, I was SO happy, I've never looked back. The upgrade from the Sovteks was larger than any tube roll I've been around. Eventually, I also installed a Mullard 5AR4 rectifier, which was more of a subtle improvement. I've been tempted about doing another kit, just to hear how the VTA board sounds in comparison.
It's funny how many folks pass over the Dynaco. Because of their availability, age, low cost, and I guess because people think if they were that special, they'd be in more expensive systems. But, I'll say this again, accepting its limits in absolute power and low end frequency extension/impact, it's the best sounding amplifier I've been around. And, that's all about the midrange. Despite having some highly respected amplifiers, none produce a better tone or sound more right than the Dynaco ST70. Not even close.