So many daring jazz musicians who hit the scene in the late '60s wound up pissing away their talent throughout the following decades -- either yapping at the heels of trends like fusion and "lite jazz" or regressing to some bland, archaic rehash of bebop. Not Dave Holland. After making his mark on Miles Davis's epochal albums In a Silent Way and Bitches Brew, the British bassist undertook many adventurous projects. Those included Circle, his short-lived but influential group with Chick Corea, Anthony Braxton and Barry Altschul, and his 1972 masterpiece, Conference of the Birds, a record full of abstraction, space and algebraic beauty. Holland also experimented with both solo recordings and the cello, culminating in his 1983 album Life Cycles, a sparse, cerebral study in texture and delicacy that (thankfully) couldn't have been more out of step with its time. For the last few years, though, he has resumed his place as the leader of his own groups, most notably the Dave Holland Quintet, which performs Friday, April 18, at the Boulder Theater. Joined by Robin Eubanks on trombone, Steve Nelson on vibes, Billy Kilson on drums and Chris Potter on alto and soprano, Holland continues to challenge his audience, his band and himself with a restless technique that embraces everything from blues to bop to avant-garde to some good, old-fashioned, full-throttle improv. Sure, the Quintet has won tons of Downbeat polls and industry awards over the last few years -- including a 2003 Grammy for its most recent album, the masterful What Goes Around -- but don't let that fool you. Holland's music has always tugged at the edges of accessibility, stretching the warmth and soul of acoustic jazz into the coolest reaches of the intellect.