I finally found the account name of the person whose music I saw without signing in back in 2009, which effectively was my first time stepping into Newgrounds. That user's name is @ForbiddenMemory.
@CaptKirky did quite a bit of prompting to me when we spoke with each other over my earliest memories of NG, and somehow, I went to Wikia, which is where ForbiddenMemory and I met under different usernames. I knew that he had music of his own, and so I looked up his links. His Newgrounds page was listed, and I saw The Icy Lands, the very first music track I listened to on here. See, seven years ago the two of us were part of a Kingdom Hearts fanon project, and we imagined up our own characters and our own background music based on what we'd learnt from the few games released then -- KH1, Chain of Memories and KH2. Shortly after listening to his work, he pointed me to @TheWeebl, which then pointed me to Weebl's Stuff.
It took me 7 years, but now I finally remember. Time to update all those statements, forum posts and interviews where I completely forgot who it was that brought me to NG first.