Review: On paper, the idea of maverick techno producer Neil Landstrumm getting together in the studio with Keith McIvor, one half of Optimo, seemed to throw up a number of potentially problematic issues. Would Landstrumm's love of noisy techno and system-levelling basslines send McIvor running? Might Optimo's wilfully eclectic side and the prospect of McIvor playing Hank Williams records non-stop drive Landstrumm mad? Thankfully, neither artist ended up killing each other and the result of this seemingly harmonious collaboration is Roca, the duo's second record as Doubleheart. It appears that in the studio, McIvor's influence has prevailed. "Grasso" is based on a slightly detuned bassline that pulses along to the sound of eerie synths and hissing percussion crackles away as an understated robotic vocal warbles away in an incoherent manner. It sounds like an outtake from one of Optimo's gloriously shambolic DJ sets, as it lurches around in an unpredictable fashion. "Crank" sets out a more intense stall, with Landstrumm's touch lurking in the background. It also centres on a lazy, lumbering groove, but the drums clang with unmistakable intensity, while the rasping percussion, visceral bassline and grimy broken beats could only come from the studio of Landstrumm. However, McIvor's side of the collaboration is quick to re-gain control and "Lizard" offers up a fusion of drugged out vocals and displaced synth lines vying with dubby off-beats for attention, like the Emperor Machine on ket. Despite this on-off tussle between two highly distinctive producers, differences are set to one side for the release's finale. There are some reference points to the other tracks, most notably on the steely drums, but in the main, "Fuentes" bears little resemblance to the rest of Roca. At its heart is a swinging calypso rhythm encased in the kind of precise percussive slivers and ticks that neither artist can lay claim to. Maybe McIvor and Landstrumm kidnapped a drunken Brazilian dancer and force fed him Rob Hood's arranging manual. Until the truth outs, if ever, it makes for a fine explanation about the provenance of this most unusual finale to a release predicated on the unpredictable.