Thinking-man’s thrash …

So you won’t admit to your heavy-metal past?

Brann Dailor doesn’t buy that attitude — he’s perfectly willing to reveal the contents of his record collection, warts and all.

“I don’t know that many musicians or people that we play with [who] aren’t into a humongous range of music,” says Dailor, the drummer for Atlanta-based metal band Mastodon.

“I [also] don’t know anybody that’s afraid to admit to guilty pleasures,” he continues. “Once you get up to your mid- to late-20s, I think the trying-to-pretend-you’re-cool thing goes away for a lot of people. If I went through my CD collection, there’d be some smiles and some frowns, probably: ‘Oh, I was hopin’ you didn’t listen to that.’ Music is such a personal thing, anyway.”

As Dailor’s talk might suggest, Mastodon zigzags a lot within any particular song — not only that, but his band’s musical freedom sounds unforced.

Almost immediately after forming in the first half of 2000, the band hit the road on a tour they booked themselves. In the past 18 months or so since the release of their first full-length, Remission (Relapse Records, 2002), Mastodon has done several American tours, plus gone to Europe three times — and once to Japan.

To describe their sound more simply than it actually is, Dailor and his band mates hover somewhere near the harsher, thrashing end of the metal spectrum. There is, however, a palpably soulful, almost blues-y rock influence beating away at the core (while a healthy dose of prog rock a la Rush and King Crimson also often rears its head).

Technical prowess and music of extremes are hardly new bedfellows. In the late ’80s, bands like Death and Morbid Angel spearheaded a trend toward technical proficiency that’s still being explored today. Across the Atlantic at roughly the same time, Britain’s Napalm Death almost single-handedly invented a style called grindcore — which, in its purest form, consists of extremely fast, short-lived, often sonically indistinct bursts of noise.

Somewhere along the way, an arty sensibility began creeping into the metal underground, and the boundaries between metal and other forms started to dissolve. (Avant-jazz figure John Zorn once compared Napalm Death’s work to ’60s free jazz.)

Well aware of the envelope’s edge, Dailor and Mastodon guitarist Bill Kelliher are both alums of Today Is The Day, arguably one of music’s most extreme acts. They also played together before that in a super-technical Rochester, N.Y., outfit ironically named Lethargy.

Mastodon’s mark might be made in their willingness now to swing the pendulum in the opposite direction — that is, to slow things down a bit.

“Look at bell-bottoms,” Dailor explains semi-sarcastically. “Bell-bottoms started off small, and they got bigger, and then there was guys walking around with the biggest f••king bell-bottoms — ‘Look at these things, you can’t even see my feet anymore!’ And then a year later, it was like, ‘Bam!,’ down to the tiniest, skinny pants. I guess maybe something like that will happen.

“I guess, for us, we want to try to make a big mish-mash of all the different things that influenced us … but not have people be able to point them out.”

Mastodon opens for Clutch at Stella Blue (31 Patton Ave.; 236-2424) on Wednesday, Jan. 21. Nebula and Every Time I Die are also on the bill. Showtime is 9 p.m.; tickets cost $17.