??? Where Does "High End" Start ???

I think it’s a tremendous service to the community to provide diligent measurements of gear that point to the most accurate reproduction capabilities! The additional angle that arises is, of course, how to effectively integrate those systems into rooms using DSP, room treatments, good speaker choices, REW, Dirac, and so forth.

That’s real hi-end stuff when you get to the point that you feel confident about your frequency response curves into Dirac from your calibrated microphone, the entire chain is sublime, and the sound is delicious!

I’ll just paraphrase U.S. Supreme Court Justice Potter Stewart’s famous quote, “I know it when I hear it”.

Entry level is what I could, with some strain, afford when I was in my teens. 

Mid-level  is what I could, with little strain, afford when after I graduated from college and got my first/second jobs.

High level  is what I could, with little to no strain, afford when I was in my mid thirties and up,

Ultra high level is what I could now purchase but probably be embarrassed to admit I had spent that much on XXXXX.,

sounds great "FOR IT's PRICE" or "Competes with products well above it's price point" or "punches well above it's price point"?

None of these suggest that there definition of “high end”.  It’s merely a comparison of components at a specific price point.