Last October, a hard-blowing young Brooklyn quartet performed at Herman's Hideaway in Denver, drawing 110 people into the 300 seat club. Fueled by front-man John Popper's flurries of piercing high notes on his harp, Blues Traveler's full-tilt marathon set clinched word-of-mouth locally, and a pocket of ardent believers multiplied in Colorado. In February, Blues Traveler sold out multiple dates at the Gothic Theatre and Boulder Theater. In July, a concert at the Denver Zoo drew a crowd of 3,800. Now the tireless band is back sporting a sophomore album, Travelers & Thieves, with a gig at Red Rocks Amphitheatre on Saturday night. And the show is doing business - nearly 6,000 people are expected. It's a phenomenon that's drawing national attention - why is Colorado the most popular market for Blues Traveler? The consensus: For a generation weaned on MTV, Blues Traveler represents the rebirth of live music as communion rather than commodity. "It's such a pain in the ass to make records, or even videos. We're musicians, not actors," the portly Popper explained recently. "The live show is our thing - we really believe in improvising and jamming. "Or fans have come to expect us to compose on stage. In a way, it's like going to sleep: we shut off what we're thinking about and go on autopilot." Blues Traveler is a "blues band" of sorts, but all kinds of extended '60s rock styles - psychedelica, jazz-rock, hard-rock - are in the group's physical, hypnotic sets. Popper, guitarist Chan Kinchla, drummer Brendan Hill and bassist Bobby Sheehan are obsessed with pushing the boundaries. Grateful Dead link Followers of the Grateful Dead have taken Blues Traveler to heart. The band members don't agree with the comparisons musically, but similarities exist - the segues between songs, the extended jams and three-hour shows. "Deadheads like the kind of music that we play - free-form pelvic rock 'n' roll that makes you groove," Sheehan explained. "The main thing we learned from the Dead is to be original," Popper added. "We don't want to lose fans because of the stereotype. We're not the next Grateful Dead, we're the first Blues Traveler. Who knows what we'll do? We may all end up dead in a hotel room from a gunfight." Popper, 23, has fit his harmonica prowess into the modern framework of rock and blues. "People were always trying to put instruments in my hand - I started to play the cello at 5, it was the piano at 8, the tuba at 10, guitar at 12, trumpet and saxophone at 16," he said. "But I was dyslexic as a kid. My guitar instructor wanted me to play "Love Me Tender" by reading the notes. I learned it by ear and had him fooled for weeks. One day I played it differently and he threw me out. It was typical of the way teachers and I got along." Considered comedy Popper listened to Lynyrd Skynyrd and Led Zeppelin early on but he entertained the notion of becoming a comedian. "Steve Martin was my biggest influence, and I was a fan of the Blues Brothers on television's "Saturday Night Live" - I couldn't get away from Jake and Elwood. Somebody told me you could play all of their songs with one harmonica, without switching keys, so I got a $10 Hohner. With the harp, I had my own pace and agenda. "I heard that Dan Aykroyd sounded like Paul Butterfield, so I got Butterfield's live album from 1971 and it knocked my socks off. Through him I discovered Elmore James, Little Walter, B.B. King and John Lee Hooker. But I wasn't serious about music until I heard Jimi Hendrix's "Voodoo Chile" and the velocity of his playing - sounding close and far away, falling. I was stunned - that was the day I wanted to be a musician." Popper and Hill met as high school students in New Jersey eight years ago. They met Kinchla in 1986, Sheehan a year later. The group got started playing at keg parties and took the name of Blues Traveler (after Gozer the Traveler, the demon in the movie "Ghostbusters"). Relocating in New York after Popper enrolled in the New School for Social Research, Blues Traveler became one of the city's most popular club bands. Impresario Bill Graham's high powered management company "discovered" the group at a benefit concert. One major label described Blues Traveler as "Charlie Parker on harmonica fronting the Meters." A self-titled 1990 debut album has sold more than 100,000 copies. The new Travelers & Thieves, produced by Jim Gaines (noted for his work with Stevie Ray Vaughan), is tighter and more controlled than the band's live jams. "All in the Groove" is the first single, and the track "Mountain Cry" features a guest appearance by Gregg Allman on keyboards and backing vocals. Concert presence But no album can realize Blues Traveler's concert presence. "The next record will be live," Popper vowed. "Our main goal is to get people to buy a ticket and jam out to live music. "Now that we have the chops down, we're into attitude and flavor. You've got to play the music of the street, but the street sounds different today. We're playing in the spirit of the blues - it's our folk music - but the blues tradition is playing what you know, what's real and matters to you, rather than trying to be trendy. "That attitude is starting to be seen and heard in new bands all across America. And it really works for Blues Traveler here in Colorado.