There's nothing at all wrong with dating a story. I have no idea where this myth came from, but a myth is all it is. "Dating" a story sets it in the real world, and I don't think I've ever read a bestselling novel set in the real world that wasn't dated in numerous ways.
And "dating", of course, doesn't stop the classics from being popular. In very large part, it's what makes Making a character be deeply into something you don't know extremely well is usually a mistake, so don't do it unless it's absolutely necessary.
If it is absolutely necessary, Google is the simple answer. I had no trouble using Google to find the most popular heavy metal bands, the ones with cult followings, the history of heavy metal, etc. Then I found it was easy to listen to nearly all these bands online, as least for as long as I could stand it. Heavy metal is not something I enjoy at all.