The quiet folk of Sean Lennon and Charlotte Kemp Muhl’s The Ghost of a Saber Tooth Tiger began an intriguing night of collaborations leading up to Yoko Ono’s SXSW closing rare performance. TGOASTT is a subdued and understated band. There’s no need to wear ear plugs for this one. But even though they’re relatively quiet, there’s something oddly compelling about their chemistry. The two complement each other well as both have soft and inviting voices. Might not necessarily knock the socks of a casual observer, but for those folk or singer-songwriter inclined, there’s something here that warrants investigation.