"However, based on the feedback from "normal" people (and a couple of musicians
), pluck can be more accurate than using a "standard" tension meter (the likes sold by DT Swiss, Park Tool and the others) - but, again, that doesn't really measure the absolute tension."
It does if you utilize a tension meter calibrator! My tension meter came with an outdated and practically useless "deflection/tension values" chart for three stainless steel spokes. And then I was servicing Mavic Ksyrium wheels with their proprietary spokes. And then CX Ray spokes, among several others. So I realized a calibration tool would be ideal. I followed Dan Burkhardt's design and quickly built one out of hardwood. Not quite as ideal as square metal tubing, but it suffices. Given all the different spoke materials and shapes today, calibrating a tension meter to spokes being used makes sense. Plus, your tension meter may get dropped or otherwise abused, so after a year or two of use, you're not going to be confident it's still calibrated.
I find this very useful as my favorite hubs, Chris King, have a 120 kgf max tension specification, so I really want to know I'm not exceeding their spec.
It's nice to know now that I do actually know my absolute tension values, as well as the fact that I'm building wheels with even tension. No more guesswork or uncertainty (within margin of error, of course!).