IMHO it is neither objectivist nor subjectivist to believe that the amplifier's job is to act like a straight wire with gain and be sonically transparent. And if amplifiers are achieving that, to the limits of human audibility, then it is neither objectivist nor subjectivist to recognise and celebrate that.
The split occurs when a particular branch of subjectivism goes all anti-science, and refuses to acknowledge that the sighted listening effect applies to audio gear comparisons, and thereby insists that sonic perceptions when comparing amps in sighted listening sessions are caused by the effect the amplifiers are having on the sound waves. Let's call this branch Sighted Listening Subjectivism. It's just a branch: it is not the whole field of subjectivism in audio. So, this is a split within subjectivism, not between subjectivism and objectivism.
Unfortunately but understandably, Sighted Listening Subjectivism is the default position for people new to the audio hobby, ie that casual sighted listening is all about the sound waves. One has to learn one's way out of this "I trust my ears, sighted" position. One learns a lot about oneself along the way, and about one's own attitude to inconvenient truths. For many, it is too inconvenient, they are too resistant, and they are having too much fun (and have misdirected too much money on the hobby) thinking that sighted listening is telling them the truth about the sound-wave contributions of audio components. They become denialistic.
But IMHO if one progresses beyond Sighted Listening Subjectivism, that does not automatically mean one becomes an audio objectivist. Especially not the type of objectivism that is portrayed as choosing gear based entirely on measurements, even if the differences in measurements are well beyond audible thresholds. People paint these things too black and white. One can be an audio subjectivist who does not subscribe to Sighted Listening Subjectivism, but still prefers to choose audio gear based on personal listening experiences, some blind, some sighted, and acknowledging that their sighted experiences are dominated by non-sonic factors.
cheers