Let me put a very different twist on this:
In the world of free capitalist economy this is all blurred. It is up to the consumer to figure out if it is worth to pay x amount of hard earned cash for a product. And it is not alwasy possible to get info on what is inside the product and what and how it actually does. In making sure the product sells a lot is left to marketing, styling, pricing etc.
On the contrary, in the world of planned economy (e.g. former soviet Union) it was a different story. Consumer electronics were classified into 5 classes: 4th class (the lowest), 3rd, 2nd, 1st and "highest". Each class had it's own set of parameters that had to be complied with by any manufacturer (THD, frequency resonse, dynamic range etc). For consumers it was easy to tell which class the product belonged to as model numbers would show this - the first figure of the model number would always indicate class: Brig 007 would be a highest class amp, Mayak 101 would be a first-class and Vesna 302 third-class tape recorder, and so on. so it was relatively easy to choose and peole would know what bang they are getting for the buck. But there were quality and reliability issues, so people had to know which makers (factories) made the units as some had beter reputations than others. The prices were fixed as well (same price in all shops), but there were supply problems. The other interesting thing is that all the units came with a compete technical documentation fully suitable for servicing the unit, complete with full circuit diagrams, so you knew excatly what you are buying. I do not think though there were any units classed as anything that can be called high end. That was left to the foreign makes.
The planned economy did not survive in the Soviet Union and free economy does so far and gives a much better choice to consumer and achieves better quality. The price for this, and that is the point here, is the consumer having to figure out what he/she is buying! And not every maker and even not every consumer magazine is helpful!
So high-end is a what you think is high-end (dpeneding on what you appreciate in a hi-fi product). And I think it means exclusivity which means high price and/or scarcity.