Hi i as most will not have heard Shindo, but i was very interested in a product he made, a cd interface. As he is coming from a analogue -valve viewpoint, the more of these type of people that take an intrest in digital sound the better for everyone.
As everyone has to make up there own mind . pre amps are more difficult to make properly maybe critical is the word than power amps.
the engineer who makes my amplification said that the shindo pre amps use transformers which can darken the sound but some people like the sound of transformers . i will ask him on this subject again and explain it a little better
the most linear valves in the book are 6n7 followed by the 6sn7
would be best for pre amp useage .I will post again on this subject when i have more definate answers .