Although the Flying Burrito Brothers was a passing phase in Gram Parsons's career between the Byrds and his solo material, the band nevertheless indicated that he'd become one of country-rock's greatest treasures. Live at the Avalon Ballroom unearths two of the Burritos' opening stints for the Grateful Dead from tapes lying dormant in the Dead's sizable vault until earlier this year. Parsons and company don't vary their set too much; a different order appears, and a few different songs differentiate one night from the other, but really that's it. The mix very much sounds like a recording from its era: no hiss, but with faint drums and keys most of the time. Both shows capture Parsons in a fine mood; highlights include the gorgeous, sleepy "Sin City," a shake-your-boots version of Hank Williams's "You Win Again" and an impassioned "Hot Burrito #1." Byrds staple and classic country cover "You're Still on my Mind" accents night two before giving way to a forced-sounding "Train Song" — one of the only hiccups. With all the documentation of Parsons's hard-to-handle persona, he sounds quite sincere throughout these two nights. The album's another reminder of this once-overlooked musician's chops — even early in his career, he was utterly convincing as a country-rocker.