Nik Bartsch

Eli Johnson / Courtesy of Big Ears Festival

At one point during the final stretch of this year's Big Ears Festival in Knoxville, Tenn., you could have pried yourself away from a distortion-jacked Sun of Goldfinger show to join a clutch of fans hurrying over to see The Art Ensemble of Chicago. In making that calculation (a typical one, for Big Ears), you'd have been weighing two wildly different experiences with one notable thing in common: Both groups have an affiliation with the sonically adventurous label ECM Records.