What happens when an underground microgenre finds itself thrust into the spotlight – as dubstep has been over the last year or so, thanks to La Roux's ­endorsement of Skream and Burial's 2008 Mercury nomination? If the second volume of Soul Jazz's annual roundup is anything to go by, it withdraws into ­itself and hopes the rest of the world goes away. While there are odd ­moments of inspired future-primitive electronica from Benga and Cluekid that transcend the genre, the indistinct, off-the-rack tropes of stoned beats, churning basslines and retro synths here quickly start to grate. Name acts such as Darkstar sit uncomfortably among the mediocrity, and are far better served on the excellent Hyperdub 5 compilation. If this is dubstep's state of the nation ­address, a constitutional ­crisis is in the offing.