I'd like to frame this a little differently for Adrian to perhaps understand it better.
We do have an expectation bias that a more expensive unit dedicated to a specific task would perform better, but as Peng says, it may perform better, but the difference is not likely to be audible!
But as far as the perception that it sounds better, don't look at it as simply the cost so much as that you have been anticipating that new amp. You have invested research in picking it and sacrificed time to earn the money to buy it.
I think food is a reasonable analogy as if you spent the last 2 hours preparing special food (or even sitting in the kitchen watching it being prepared), the anticipation is going to result in heightened attention to the taste of the food and you will enjoy it more than you would if you just walked in the door (not thinking about food)!
Similarly, if we spent the last 1/2 hour driving home thinking about listening to a favorite song on our system, that song will generally sound more profoundly great than it would if it just popped up on a shuffle play.
You can look at it as being more alert to the sound and thus taking in a little more nuance than you otherwise might, or you can think of it as biochemical endorphins/stimulants that your body generates from your anticipation!
In the end, we humans are ill-suited to doing fine comparisons of our sensory inputs. If you consider color, we use paint chips to ID the color we want with a bit of precision, because we know we cannot remember the exact specifics of a color to the level of precision that the paint chips offer. Sound is maybe even less so and there is no "paint chip" for sound!
Yeah, you can hear the difference between very good and poor speakers, but the difference between speakers is humongous when compared to the difference between modern competently designed amps (unless you are overloading one of the amps so it is not performing as designed)!
On the Crown, I would postpone judgement until you have the source of the noise resolved. It certainly has the potential to impact the sound!
Even so you simply cannot trust your ears unless you have removed knowledge of what you are listening to. That is why rigorous research requires double-blind testing!
Just as a fun demonstration of how our eyes can override what our ears hear, here is a 2 minute clip on the McGurk effect:
