Guitars play chords. Which means when you put four of them together, as local guitar quartet Dither did at The Flea this past Monday, you get an almost endless range of possibilities. It can sound tight and regimented (as on Fred Frith's "The As Usual Dance...") or organlike (Arvo Part's "Pari Intervallo.') But even then you don't have the decay or drastic voicing guitars give you, with their vast array of effects pedals and dampers. "It's really hard to write for guitar quartet," said Simon Kafka, one of the four Dither players (which also includes Taylor Levine, James Moore and Josh Lopes.) I can believe it. (More pics below.)