Now, here's the problem. There aren't any instrumental measures that tell us what we want to know. There is just no way yet available of measuring a hi-fi reproduction system to tell us how accurate it actually is.
Of course there are. What makes you think otherwise? We can measure the distortion in any audio component, to as many decimal places as your heart might desire. We can measure the impact of the room itself. That's what room correction does.
There are good ways to tell us whether amplifiers distort electrical signals, but while that's relevant, it doesn't tell us what we want to know.
It tells us something that many of us want to know. What is it that you want to know?
When I kick back and put on a recording of my favorite opera, I am just not that interested in whether my hi-fi system is giving me an accurate rendition of the electrical signals recorded on the cd (or whatever other medium). That's not what's relevant.
To you, perhaps. But I think your approach to audio is perverse.
So, could the scientists and engineers please give us ways of measuring the accuracy of sound reproduction systems?
They exist, and are widely used. What makes you think otherwise?
Until they do, what alternative do we have to listening and doing our best to evaluate hi-fi systems impressionistically?
How do you know what your impressions are based on? There are three possibilities:
1) You are hearing real differences in sound quality.
2) You are hearings differences in volume levels, which your brain is interpreting as differences in sound quality.
3) You are imagining differences in sound quality.
Which is it? The purpose of measurements and DBTs is to answer that question. To some of us, it's an important question. To others, it appear to be very threatening.