Strange; although I agree with all of the previous descriptions, I will attempt to give one. Mid Fi is mass produced, and the top end of Mid Fi can sound very good. When you go beyond this point, the price escalates, for many reasons, and the sound becomes more refined. The law of "Diminishing returns" also kicks in. Since many people can not hear what is a much larger price differential than an audible one; they disavow the distinction.
The bottom line is, "What ever definition that floats your boat" is just fine
The bottom line is, "What ever definition that floats your boat" is just fine