Portastatic began as a solo side project of Superchunk frontman Mac McCaughan in the early '90s. Early releases were essentially lo-fi, four-track recordings of would-be Superchunk songs. Through the rest of the decade, Portastatic evolved as a forum for McCaughan to experiment with bossa nova, tropicalia, and film scores.
Eventually, as Superchunk settled down, Portastatic became a full-band. The three big "rock sounding" albums are all great - and definitely some of the most underrated of this decade - but the best is 2005's Bright Ideas.