BRAD MEHLDAU Live in Marciac [Nonesuch] Brad Mehldau’s restlessness is as much a force of nature as his musicianship, so it comes as no great shock that the master jazz pianist follows last year’s double-disc quintet recording Highway Rider with another double album (plus DVD), this time solo. Mehldau is an explorer, in his compositions, his playing and—to the delight of his loyal flock—his eclectic choice of cover material. The music he interpreted...