I wish I could be more helpful. I am an enthusiast, not an audiophile. Also my ears have been exposed to some really good times over the years.
Subjectively, I can appreciate the sound quality of the TB, but not sure I could tell the difference in sound quality from using different power supplies with it.
For those that are more acoustically discerning, I would assume the improvement could be quantified, both subjectively and objectively.
As with most critical tests, I would assume the test data presented by Khadas was gathered under best-case-scenario conditions. In other words, the Specs shown for the TB were most likely produced using the best type of power supply for the job, of course, I speculate.
While there may be gains using a linear power supply vs USB/Wallwart, in any case, I would not think any gain in performance would be in excess of the TB Spec sheet.
Maybe try the standard type PS first, you might be satisfied. If after auditioning the TB, you want the maximum performance achievable, you might look in to the linear option.
Hopefully one of the more acoustically discerning TB users can offer you more sound advice, pun intended.