Because the D.C. scene is mostly about three chords, a red guitar, and the truth (just like U2, though I suppose that list would now have to include a disco ball), the monophonic, analog-keyboard, and vocalless Cul de Sac stands as much chance of drawing a crowd tonight as Randy Travis at the Apollo. But those few who can brave the absence of typical song structures will be treated to a galvanizing compendium of Krautrockisms, from heads-down hypnosis to heaving hallucinations. Both last year’s Ecim and the recently reissued I Don’t Want to Go to Bed are dizzying displays of late-night searches for the lost chord, one note at a time. With Tone at 8:30 p.m. at the Black Cat, 1831 14th St. NW. $5. (202) 667-7960. (CP)