Colorado-based singer/songwriter Gregory Alan Isakov [2]'s appeal is subtle. His voice is soft and his songs are sparse. Yet, despite his introverted approach--especially in light of common ideas about pop music's extroverted prerequisites (monster egos and domineering performances)--Isakov is mesmerizing. His music doesn't shout and clamor for your attention. It simply waits for you, confidently, like an open-armed invitation. Born in Johannesburg, South Africa, Isakov brings a world-wise, wide-angle perspective to his songs. On his latest LP, "That Sea, The Gambler," he explores ideas of love and travel, and how a hefty toll is paid for indulging in both. Though the songs hardly vary from their leisurely tempo and lean atmospheric accompaniment, the album takes ages to get old. Especially during this snowed-in, reflective part of the year, Isakov's aura is as comfy as a pair of trusty socks. Recently, Isakov has been recording a new album and getting major props from Amy Ray of folk veterans the Indigo Girls [3] (the two are playing a Colorado show [4] together in early February) and Seattle-based singer/songwriter Brandi Carlile [5]. Isakov plays an acoustic set tonight along with Tiny Television [6], Jefferson Hamer [7], and Reed Foehl [8]. The show is presented by HomeVibe [9], which presents shows in smaller venues with a living-room intimacy in mind. 7:30 p.m. The Walnut Room [10], 3131 Walnut St., Denver. $15. Ages 21+. 303-292-0529