Garam will definitely change for sure especially in the up coming chapters. I hope that he doesn't turn into Heejae in the sense that all he cares about is the purity of music. I lowkey thought that he would crash out if the sound didn't right and I feel like he's getting habits from Heejae. It's possible that the more famous he gets the more he cares about the purity of the music. Like nitpicking every single thing like Heejae did at the start of the story.
Actually ima add on to that perfectionist realm that Garam is going into. The recent chapter has shown us that he got like tremors if it wasn't the way he wanted but after Compton fixed what was wrong the tremor stopped. If this was Garam back then like during the Christmas arc over 80 chapters ago then he wouldn't have mind the ever so little details. For example, the people eating during the Christmas performance he didn't care. But now, if he played that Christmas piece then he would probably start being shakey again.
Simply, Garam cares about the purity of the sound after being exposed to what a perfect symphony sounds like / feels.

I’ve read a couple of comments saying they’re scared of Garam changing and not appreciating the music if there’s no piano.
In a way, I understand but isn’t that common to “bitch” about other tastes/professions once you become good at one? Like for example all the hype that happens everywhere of becoming a Doctor, but those that are already doctors and specialize in a particular subject feel more entitled to criticize: cardiology is better, no plastic surgery is better bc of money, no psychiatry is all about the mind, no the top of the top is neurologist… and so on and on.
Now with music and in this scenario I feel is the same. A violinist could think they’re better than a pianist but both will feel better than a flautist and so on and on… so Garam won’t stop enjoying music, the professor loves music (it has been drawn how much he enjoys jazz) but if you perfect something maybe some pieces will feel mild or plain if a piano isn’t there because they know how to play it. For them that’s the top cherry… and I feel it’s a valid sentiment.
So, yes fame could change him but not to the extent of him not enjoying music at all. I think here is more about getting into the realm of perfectionist/ love for his instrument rather than fame.
Thank you for reading this haha
(づ ̄ ³ ̄)づ