Hearing the opening of The xx's single "Intro" (featured during the Olympics on an AT&T commercial with speed-skater Apolo Ohno) the broiling mass of humanity that filled the French Legation grounds in East Austin Thursday evening let out a collective sigh.

The late-starting set was one of the year's biggest buzz bands launching its SXSW assault, playing its first of many showcases. Yet The xx is one of those new British bands - think Bloc Party or White Lies - that doesn't really seem suited for sunny festival settings. Sex and dark moods shape their songs, so while they played their quasi-hits "Crystallize" and "Islands," the energy remained diffuse.

The lyrics were muted. Listeners turned to conversation and heckling one and other rather that digging the band. One hopes the singer-guitarist Romy Madley-Croft finds her inner belter this week. Certainly, on the winning "Infinity," with a guitar line that sounds suspiciously similar Chris Issak's "Wicked Game," the band showed charisma.

Alas, The xx were gone from this showcase before we got better acquainted.

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