The best "boutique" op amps perform about the same as the quality op amps from the likes of Texas Instruments. However certainly not better and cost significantly more, 10 or 20x. Some of these boutique parts perform significantly worse.
There is just no technical logic to implement them, but they do appeal to audiophiles and they can be charged more for the privilege.
Now, the op amp is one thing but there is a lot more to the final performance of the buffer. Board layout has an impact. Different caps and resistors have different distortion characteristics. Regulators need to be suitable for rejecting the smps high frequency noise. Standard regs are poor in this respect.
So just because a board contains "op amp X" does not mean it has good technical performance or sounds better.