For me, that's a bit of an odd question, at least in the early days. In high school, I really wasn't into a particular style of music until my senior year, and by then, I'd kind of given up D&D for games like Traveller and Top Secret. The only song that really makes me remember those early days is the rather less than good "Hold the Line" from Toto, which always reminds me of sitting in my room on New Year's Eve 1978, keying a dungeon.
By the time I got into hard rock and metal, I had moved on to games like RuneQuest and Stormbringer. For that period, Blue Oyster Cult, Rush, and Iron Maiden were the soundtracks of my life, but I still didn't really mix gaming and music. At least, not directly. I certainly cribbed heavily from BOC for my Stormbringer games (f'rinstance, the holy symbol of Chardros the Reaper was their logo in my version of the Young Kingdoms).
By 1982 or so, I was heavily in Champions' embrace, and, apart from the "Superman" soundtrack, there wasn't a lot of music that screamed "superheroes" out there back in the day.
I "rediscovered" AD&D, so to speak, when I was working in a bookstore and got everything at 40% off. Also, we carried Dragon, and that's when I started reading it regularly for the first time in years. That got me back to thinking about AD&D, though I still didn't play it often. But musically, it didn't sound like metal to me. Nope, mid-80s AD&D sounded like this:
(In my version of Faerun, this is the national anthem of Myth Drannor)
I still wasn't using music in my games, but that show, and the album renewed my interest in things medieval fantasy in a big way, and I was obsessed with capturing the sense of "historical myth" it did so well in my games.
Even into 2nd Edition, I was far more likely to use medieval or renaissance music to inspire my games. I didn't actually use it while playing, but I'd have it on in the background while noodling maps. The first time I really remember being faced with the idea of using music as a backdrop for my games was reading the boxed first edition of Cyberpunk. It had a section on creating atmosphere and even included musical suggestions. This was, to me, an entirely new idea and I went more than a little overboard with it. I'm pretty sure that some of my game mix-tapes ran longer than the campaigns they were recorded for.
But the genie was out of the bottle, and music became one of my things. Used sparingly, it worked pretty well.
Then, 3e/D20 came along. And 3.5. Right around the same time I discovered Power Metal, one of my true guilty pleasures. Almost entirely European in origin, it eschews the growly yarl of most mainstream metal, harkening back to the 80s, when lead singers actually, y'know, sang. And the subject matter is pure fantasy geekgasm writ large. I could go on, but it's easier to let some of this stuff speak for itself:
Yeah, that's Christopher Lee, wearing a crown and robes and narrating. For reals.
This one's actually about Raistlin Majere, from "DragonLance." I am not making this up.
Though I do like SOME growly stuff. If the subject matter's good and I can understand the words.
Fact is, I enjoy this particular genre so much, I made up a Pandora station entirely focused on it. If it sounds like your thing, you should check it out. It's pretty much how both 3rd and 4th editions sound to me these days. Pathfinder too. Probably all subsequent versions of the game.
So what's D&D sound like to you?