Hermann Keller, a composer and pianist, has been daring to approach and stretch limits ever since he first started to write music. For Keller, each music-making activity involves the exploration and testing of his timbral material. Far from proceeding purely theoretically, he does this by gathering experience on the instruments for which he writes. One feature of his combination of jazz and contemporary composition is a sense of restlessness and discontent, of rebellion and escape, that typifies his music as a whole. The conflictive potential resulting from this symbiosis, combined with acrid timbres bordering on the shrill and discordant, gives Keller's music it's tension.