This has been an interesting discussion to follow and I read @nhatlam96 thought process as one many of us have had in the beginning: 1+1 = 2
But there are so many elements to a dac and an amp so just because 2 dacs uses the same AKM4490 chip it doesn’t mean they sound the same, regardles if you or your mates can’t hear any difference.
And as anyone interested in hi-fi quickly finds out and so many has stated already: ears and people are different.
When reading nhatlam96’s thoughts and approach to this I just think: dude, go out and try it out, what you are doing, trying to reason your way to the right gear and almost see it as an equation is futile.
And part of this hobby is to try different stuff, not to solve a math equation 
So enjoy the hunt for your gear; enjoy the different sounds you get from said gear; don’t reason your way to it solely (as a part of the hunt it is okay, bc we do look at what chip a dac has) and don’t rush to your endgame too quickly - the journey is actually part of the fun 
Enjoy the hobby my man and as my fellow Dane Soren Kirkegaard once said:
