Notes from the fella who told me about this gig:

3/20/99 (technically 3/21, as the set was at 2am), BTS played another show in Austin - this one was in a huge downstairs room at a building who's name escapes me - it was a Spin Magazine private party that they do annually for the last nite of South By Southwest. the bill was - 2AM - Built To Spill, 3:30AM - Flaming Lips, 5AM - Juan Atkins (DJ). i was at this, they did like a 50-60min set. rumor had it that they played another party or something on 3/19 but i'm not sure. somewhere i have a flier for this show and when i dig it up i'll let you know the venue.