“Hmmm, let’s see now...the ’57 Gretsch or the ’58 Goldtop?” Joe Walsh contemplates a bevy of highly collectible vintage guitars strewn in open cases across the floor of a Hollywood photo studio. Broad shouldered and looking fit, he towers over the instruments, meditatively stroking his chin. A Guitar World cover shoot is serious business, and Walsh brings to it consummate professionalism that has guided him through over four and a half decades as a classic-rock guitar legend.

It's 11 a.m. on the day after Halloween, in the Koreatown neighborhood of Los Angeles. The sun is shining and Guitar World is up bright and early (well, at least by rock-star standards) to meet with Mastodon at the Wiltern Theatre.

The blues tradition runs deep in Texas, which has produced a constant stream of innovative blues guitarists, including T-Bone Walker, Lightnin’ Hopkins, Freddie King, Clarence “Gatemouth” Brown, Albert Collins, Billy Gibbons and Jimmie and Stevie Ray Vaughan.

Lamb of God’s first blatant attempt at expanding their sound—and the receptiveness of their audience—was heard on 2009’s Wrath. On that record, they moved away from the multitracked guitars and modern production of the massively popular Sacrament and returned to a purer live guitar sound.