I used to compile the music listings for this paper. I'm glad I don't do it anymore--deciding what category certain artists belong in has turned into an ontological riddle. As more musicians trample over the boundaries between jazz, free improvisation, rock, noise, electronic music, and contemporary classical, it's not only more difficult to label their work, but doing so misses the point altogether. Icelandic guitarist Hilmar Jensson is a perfect example: he got his start playing jazz and came to America to study at Berklee, where he became friendly with broad-minded players like drummer Jim Black and reedist Andrew D'Angelo, who round out the trio he brings to Chicago this week. He studied with jazz heavies like Jerry Bergonzi, Mick Goodrick, and Joe Lovano, but for the last decade, during which he's been based in his native Reykjavik, he's generally collaborated with experimental-rock types, working extensively with fellow Icelander Skuli Sverrisson and as a member of the arts collective Kitchen Motors. Jensson mashed his experience together on last year's Tyft (Songlines), recorded with Black and D'Angelo. Here the music is like a plucky ship navigating a sea that shifts from rough to calm in the blink of an eye. Although there are kernels of composed material, most of it is improvised; all three musicians are also keen on electronics, laptop fuckery, and found voices. Black, who can do both explosive drum 'n' bass snippets and floor-rumbling freak-outs, steers the boat; sometimes Jensson and D'Angelo, on astringent alto saxophone, play knotty unison lines that slalom through the beats, or they join the din with feedback and overblown squeals. But Jensson plays bona fide chords on an acoustic guitar as often as he plays around with effects, and D'Angelo can add rich harmonic color when he's not blowing ferociously. (D'Angelo also performs in a more traditional jazz setting this Friday and Saturday night at the Green Mill as a member of the Matt Wilson Quartet, which has an excellent new Ornette-ish album on Palmetto called Humidity.) Wednesday, April 9, 8 PM, Empty Bottle, 1035 N. Western; 773-276-3600.