Since the xx pushed through planning permission for the regeneration of soul music, it's become a vibrant hotbed of invention, retro-Motown warbles mingling with modernist sonic skulduggery until you can't tell where the mainstream ends and the leftfield begins.

The likes of James Blake, London Grammar and Jessie Ware are thriving there and it's where Joan As Police Woman, AKA one-time lover of Jeff Buckley, Anthony Hegarty collaborator Joan Wasser, has found a new precinct to patrol.

The indie torch-song aesthetic of her early material, stricken with grief for Buckley and her mother, has gradually morphed into an accessible soul adventurism on fifth album The Classic, a break for the big time thatcreates an intriguing but disjointed live experience. One minute she's a cruise-ship Adele (What Would You Do) or Shania Twain doing northern soul (Holy City), the next she's summoning gargling demons with a ceremonial golden violin on New Year's Day or uncaging a pack of rabid Mogwais to whip up a post-rock hell-storm at the end of the seven-minute dusky blues Good Together.

For every edgy stab at splicing Foals and Massive Attack on Get Direct or experiment in afrobeat rap on Let It Be You, there's a straight-ahead jazz soul, reggae or Latino pop number to calm the horses. It's unclear whether she wants to seduce the Winehouse crowd or pervert them.

Ultimately she charms more than she challenges, whether with gorgeous toy-box laments such as Feed the Light and Your Song, which are so delicate they're often drowned out by the hand-dryers in the venue's toilets, an a capella barbershop version of The Classic or face-fanning claims that "I'm gonna go backstage and cry now".

Inviting the retro-soul mainstream to open its mind and desert its comfort zone is like asking Birmingham to move a little to the left, but thank heavens artists such as Wasser are trying.