Let me weigh in here as, I believe, the first customer for Roy's VTA SP14... Or at least I tried to be. Ordered it as soon as he came in line to report what he had cooked up.
Since then, of course, I've dumped this piece of crap....
Heh heh heh JUST kidding!
You know, over on the Transcendent forum, go check... You will often read assertions that the Grounded Grid is about as good a pre amp as you'll find under anywhere between $5k to infinite.
Well, ai have one, and it is great, but I replaced with an SP10 (was it a "10" Roy?), and it was much better, but at about the same price.
Then came the SP 14, and this was before oil went to $9.95, taking Alberta's economy with it.
To cease making a short story too long, the SP 14 is not just "way better", it's stunningly better. Transcendent would never sell another GG if customers heard this. It's truly a staggeringly good pre amp.
Make no mistake, though. The SP 14 is merely part of a broader conspiracy. The same people are responsible, culpable indeed for other acts of audio sedition.
Between Roy and Bob, they have brought uodates and modifications to the original Dynaco design that will simply make you weap when you hear real music played through these products.
I say experiment, by all means, but I sugest after, not before or instead of building a VTA kit. Start with the best kit available, then improve on it if you can.