Question: How do you find a tube preamp and tube amp if your goal is absolute neutrality?
Ideally you would want to have a properly treated listening room to play your audio in, in order to be able to properly assess the playback. Evaluating gear in a less than optimal room will make differences harder to hear.
The next thing would be to have speakers that have a flat a response as possible, as full range as possible, and be as benign a load to an amplifier as possible. Personally, IME, I would want a speaker with as low a crossover point between the tweeter and midrange as possible, and where the midrange does not have to go and play too low either. This makes the midrange performance of the speaker much cleaner.
I'll omit discussions of speaker cables and IC's and so forth, as that can be a topic onto itself.
And finally, you need to have a great reference recording. For that, you would probably be best with a minimalistic recorded classical orchestra piece, or acoustic jazz ensemble. Also, something with well recorded vocals, as humans are most familiar with the sound of the human voice.
When I talk of neutral, I think of FR response and timbre. When I talk of transparency, it means faithfullness to the original event, I talk of neutral FR, and leading edge transient response, as the first few milliseconds of any leading edge are critical to the quality of transparency of any musical "event", be it the crack of stick on a snare drum or the attack of the bow on a stringed instrument etc..
Dynamics are critical as well.
Also, I think a mix of critical listening, and more relaxed listening between components over a period of time is probably a good idea. I usually focus on mid's only, then high's and lows later. So it takes me a bit of back and forth. Trying to assess it all at the same time is too difficult for me. Taking notes helps as well.
Cheers
