With his plain speaking voice and youthful good looks — ruddy cheeks, square jaw, flat-top crew cut, red Converse high-tops, and round-turned baseball cap — Ken Vandermark comes across like a gang-bangin’ George Jones. That is, until he puts the tenor sax to his lips and exhales high-octane flames.

“Coleman Hawkins can blow a note and the energy of the note says something,” he says, distilling a notion from the swing-era tenor giant whose music is a far cry from Vandermark’s. “It’s not just making a statement with authority and not just playing a note in the right place at the right time, but the energy within the sound.”

That intensity, that “sound,” is something Vandermark has been crafting on tenor saxophone (and clarinet, and bass clarinet) since college, when his father turned him on to Joe McPhee’s solo album Tenor. Along with further insights gathered from the music of pianist Cecil Taylor and alto saxophonist Jimmy Lyons and, later, Polish composer Witold Lutoslawski, McPhee’s record inspired Vandermark to emphasize flow and energy in his playing and writing. “I’d heard some free stuff and it sounded to me like people just squonking around. Here’s McPhee, making just as much noise, but all the concept of melody and structure was totally there. It was like: ‘That’s it! That’s what I want to do!’ It totally floored me.”

In Boston in the late ’80s, Vandermark worked with his first group, the Lombard Street Trio. In 1989, he relocated to Chicago. Last year, after a disheartening period in the apathetic Windy City scene, the wind player decided to pack up and move back to Boston, a town he admittedly hates. But percussionist Michael Zerang convinced him to try one more year in Chicago. Upon agreeing, Vandermark suddenly found himself awash in work and up to his ears in opportunities.

In fact, he takes his burly free jazz to the stage at least twice a week with one of the five bands he regularly plays in: Caffeine, a free improvising trio with keyboardist Jim Baker and drummer Steve Hunt; the Flying Luttenbachers, a self-proclaimed “punk-jazz” trio with saxist Chad Organ and percussionist Weasel Walter; the Waste Kings, an “MC5-ish, Troggs-ish” rock band with former members of God’s Acre and the Sapphires; and the NRG Ensemble, the late Hal Russell’s quintet. Vandermark also plays with old Boston friends, including Lombard Street drummer Curt Newton and his band Debris, whose new disc Terre Haute (Rastascan) includes a dedication tune “4KV.”

Vandermark has secured a weekly stint at Hot House (the hippest club in Chicago’s bohemian, soon-to-be-yuppie Wicker Park) with his own Ken Vandermark Quartet, featuring Zerang, bassist Kent Kessler, and guitarist Todd Colburn. The group — whose first CD, Big Head Eddie, is now out on Platypus — plays incendiary music, obviously influenced by the melodic mindset of Ornette Coleman and Henry Threadgill, but also propelled by rock.

“To me, you’ve got something written: OK, make it flexible so things can change. And leave it open so people can interject things constantly to provoke the soloist” — he raises his voice animatedly — “like how much information can you throw at this guy, you know?”

In all his musical chairs, Vandermark looks for the same kind of strength-of-purpose and here-today force. “One of the best things I’ve heard is what drummer Han Bennink said in an Eric Dolphy documentary: They asked him what it was like to play, and he said, ‘Every time I play I feel like I’ve got my back against the wall, ’cause I don’t know if it’s gonna be the last time.’ That’s the whole thing! When you step onstage to play in front of people, why be there if you’re not there to play your ass off?”