The since-popular jazz pastime of covering Radiohead helped announce The Bad Plus to the world. Their own compositions actually dominate a 16-year career, which hasn't resorted to the modern songbook since 2008's For All I Care. It's Hard returns to an MO which has been sniffed at by some, with sources ranging from Kraftwerk to Crowded House. This diversity seems gimmicky, but has a cumulative strength. Yeah Yeah Yeahs' ‘Maps’ is all skittering, tumbledown turmoil, Ethan Iverson's piano stabbing out melodic moorings. Cyndi Lauper's ‘Time After Time’, once a Miles bid for the mainstream, drags then races as tempi pull apart, in a part-minimalist meditation on the tune. Such musically rigorous, borderless enquiry surprises best with ‘I Walk the Line’, which atmospherically conjures a 1940s interzone where Johnny Cash jostles at a honkytonk with Aaron Copland and Fats Waller. Pop's harmonic resources are explored, its emotional pull retained. ‘The Beautiful Ones’, by the jazz-minded Prince, has its melody stated with dark melancholy, its funk located by Reid Anderson's bass, and cascading raindrops of piano leading to an uninhibited climax. The Barry Manilow favourite ‘Mandy’'s pensive prelude suggests a Ryuichi Sakamoto soundtrack, before glorying in the tune's schmaltzy power. Though a soft way to connect, these songs are done the hard way, with an underlying message: don't fight it, feel it.