What's your definition of "jaw dropping"?
Let's be honest - humans are emotional beings.
In general items cost more only if folks are willing to pay the higher price.
Are there $5k integrated amplifies that sound better than an $8k integrated amplifier - it's definitely in the realm of possibility.
If you look at established high quality brands - within their product lines there will be a difference in the integrated amps at various price points. McIntosh has integrated amps at $5k and $8k and there's differences...I don't know if they are earth shattering.
If you look at other brands - say NAD or Rogue and you'll experience a difference in sound as you go up the model range. And you'll notice a difference between the brands at the same price point.
When comparing a SS versus Tube and Class AB versus Class D you may hear a drastic presentation. And that can be very personal.
And there's going to be someone that states - you can great quality system for less than $1k all in...and you can.
In the end, I try to enjoy my system as is. Why? Because the goal for me is to enjoy listening to music.