Thanks for letting me be a part of the tour, it was great being able to try out the preamp!
I work in a job where I deal with a lot of analytical chemistry and analysis, particularly concerning botanical extracts so my stance on measurements is a little bit different. I think everything has to be explainable by analysis, otherwise, we are dealing in the realm of fairy dust and magic, and that does not sit well with me. That being said, low distortion values is clearly not what it is all about, it is a lot more complex. Some distortion may even be slightly desirable, or perhaps a bit of compression from a buffer stage. Then we also start getting into the realm of very minor pre-set tone controls basically, helping to enhance the sound. Perfection in distortion and engineering may just be boring for most music listening. However, I still believe we can quantify this with measurements, we may just need to expand that scope and factor in psychoacoustics and even room acoustics, something a standard analysis rig is obviously not taking into account for electronics like amps, DACS and preamps.
That all being said, we all have our own little measurement rig, and those are our ears and when it comes to enjoying music, I agree that's the measurement rig we should rely on most. Still, I would like to see these preferences be explained by science and analysis because liking the way something sounds, corresponds to something physical in the world that is quantifiable yet subjective. The subjectivity part, differences in ear shapes, processing of audio signals in our brains, the frequency response of our ears and just simply personal preference, is where things obviously start to get incredibly difficult.
I like your example of buying wine according to a chromatogram, and to be honest if that were possible that is how I would be buying my wine haha. I could over time identify for example that out of the different acids that can exist in wine such as lactic acid, citric acid, tartaric acid, malic acid and phosphoric acid that I may prefer the acidity of wines high in phosphoric acid while not liking wines that derive most of their acidity from citric acid. If a chromatogram was available on each wine bottle, that would then allow me to pick the wine that best suits my palate. Currently, it's more of a guessing game (and so is the majority of audio to be honest) I think the reason people don't buy wine according to chromatograms is because it is not available and would require a fair amount of education. However, I think if it was available it would be very popular. I hope that one-day analytical chemistry becomes cheap and fast enough where these sort of things are more available to consumers. It's already being used on the production side of things, just look at all the work Anton Paar is doing, a good deal of their analytical equipment these days is catered towards beer brewing and wine production. I think what they are doing on Audio Science Review is fantastic because it gives consumers access to analytical data that most of the manufacturers already have access to anyways and often lie about to their customers too when they do make results available. That being said, they are playing a dangerous game sometimes by only going for low distortion stuff and not taking into account all of the other intricacies of good audio engineering.
Anyways, long story short, I really enjoyed listening to the pre-amp, it sounded very fun and pleasant and I would not at all mind having one in my system! Especially taking into account that the minor bugs have been fixed in the production models!