C'mon, @amirm, if you believe DACs on different ends of your color-coded chart are audibly different (on music at normal listening loudness), then do a proper blind ABX test and prove that they are audibly different.
So you don't have any proof of the universal claim you made. And further, can't indicate how the OP would save money by picking from lower tier products.
And no, I am not here to disprove your claim. You need to take the worst performing DACs and conduct your own transparency tests before saying hundreds of DACs are indistinguishable from each other.
But answering anyway, I have passed such "impossible" tests. Here is one that Ethan Winer had post where he took the output of his DAC, ran it through its ADC and made multiple generations of it. He was confident no one would be able to pass it. Yet, here are my results:
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Here is an example test you can take to show us you do have good hearing acuity.
https://ethanwiner.com/loop-back.htm
It is a piece of music that has gone through a DAC, then ADC, then back to DAC and so on. And on really bad DAC/ADC as audiophile standard go: a $25 Soundblaster X-Fi.
This is me finding the difference double blind with just one pass through DAC/ADC:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/18 06:40:07
File A: C:\Users\Amir\Music\Ethan Soundblaster\sb20x_original.wav
File B: C:\Users\Amir\Music\Ethan Soundblaster\sb20x_pass1.wav
06:40:07 : Test started.
06:41:03 : 01/01 50.0%
06:41:16 : 02/02 25.0%
06:41:24 : 03/03 12.5%
06:41:33 : 04/04 6.3%
06:41:53 : 05/05 3.1%
06:42:02 : 06/06 1.6%
06:42:22 : 07/07 0.8%
06:42:34 : 08/08 0.4%
06:42:43 : 09/09 0.2%
06:42:56 : 10/10 0.1%
06:43:08 : 11/11 0.0%
06:43:16 : Test finished.
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Total: 11/11 (0.0%)
And of course with 20 loops:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/18 05:38:16
File A: C:\Users\Amir\Music\Ethan Soundblaster\sb20x_original.wav
File B: C:\Users\Amir\Music\Ethan Soundblaster\sb20x_pass20.wav
05:38:16 : Test started.
05:39:05 : 00/01 100.0%
05:39:27 : 00/02 100.0%
05:39:44 : 01/03 87.5%
05:40:01 : 02/04 68.8%
05:40:18 : 02/05 81.3%
05:40:30 : 03/06 65.6%
05:40:58 : 04/07 50.0%
05:41:09 : 05/08 36.3%
05:41:19 : 06/09 25.4%
05:41:28 : 07/10 17.2%
05:41:38 : 08/11 11.3%
05:41:53 : 09/12 7.3%
05:42:02 : 10/13 4.6%
05:42:18 : 11/14 2.9%
05:42:29 : 12/15 1.8%
05:42:42 : 13/16 1.1%
05:42:53 : 14/17 0.6%
05:43:03 : 15/18 0.4%
05:43:16 : 16/19 0.2%
05:43:27 : 17/20 0.1%
05:43:40 : 18/21 0.1%
05:43:53 : 19/22 0.0%
05:43:58 : Test finished.
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Total: 19/22 (0.0%)
As you see, 0% of guessing.
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So stop with hand waiving arguments. Countless DACs will have audible noise floors depending on how much you amplify their output, i.e. max SPL. There are peer reviewed research papers indicating what you need for full transparency. I have written articles on it and done videos as well. Distortion will be harder but not in the case of products with strong non-linearities.
It is this kind of argument that keeps people from landing on the simple conclusion that OP found. That you do well to buy the products in blue categories. That sharply increases your chances of transparency with zero cost to you as there are countless options there. Anything else lands you in a gray zone that you can't dig your way out of.