Audio electronics have been transparent to the source for several decades - contrary to what the manufacturers want you to believe!
If this is correct, can you explain the tubes/solid state that's been going on for so long? The tube guys assert that most solid state is harsh and bright or lean and dry. The solid state guys say the tube amps are colored due to FR variation and the 2nd harmonic. IME there is truth to both positions.
The publications have declared war on blind testing exactly because most components sound virtually identical. The entire industry is founded on expectation and confirmation bias.
IME this statement is problematic. While there is lots of confirmation bias, IMO its false to say the industry is founded on it! And that's because the first statement is false. There are still plenty of differences you can hear between competent equipment and IME you can measure those differences too.
There's an on-going argument decades old between the subjectivist and objectivist camps. I'm of the opinion that if you can hear a difference, you can measure it too. Both camps hate that (and this has to do with confirmation bias of which both camps are guilty). If real progress is to be made, that has to stop. Sure, lots of solid state equipment sounds the same- and IMO/IME, most of it also has the same solvable problems (insufficient, poorly applied feedback, insufficient Gain Bandwidth Product..). There are solvable issues on the tube side as well, where you are far more likely to hear bigger differences.
I can say from direct experience that advertising does not affect the reviews in TAS. I can also say from direct experience that is most definitely does in Stereophile. I can't say at all for any of the other magazines as I have less experience with them, but for the most part my limited experiences suggest they keep a decent firewall between editorial and advertising. I have also seen some pretty underhanded stuff go on- no organization is entirely squeaky clean.