stereo system evaluation--objective or subjective

Isn't it interesting that some British recording artists lose their accent while singing and some Americans gain one :)
Or is it just my ears?

That would mean removing subjectivity and using only technical data. I wonder to what extent design engineers use their ears. There is a fairly large margin of predictability towards a particular desired outcome but I would think a lot of trial and error goes into prototyping any piece of gear before a final rendition is settled on. So I guess I've answered my own question.