First, a confession. Music journalists don't actually listen to every album that comes out; every album we review, of course, but there simply aren't enough hours in our gig-economy, part-time-contributor week to hear everything. So, when we’re faced with someone we don’t know that much about, the review process usually starts with going back and sampling as much of that artist's previous output as is practical, to set the new release in its proper context. No record is created in a vacuum, except perhaps the sixth or seventh in a sequence of dozens. You have to read around.

Saying that, it's all too easy to overlook the occasional gem, and Girlpool's debut long player is one such example that, frankly, passed me by. That record, Before the World Was Big is startlingly fresh. This one, Powerplant, tells a slightly different story.

LA locals Harmony Tividad and Cleo Tucker share the kind of preternatural understanding that scares naive parents in B-movie horrors, despite not actually being blood related. Like a West Coast retelling of Heavenly Creatures, the pair have fashioned a world all for themselves with its own logic, colour palette and a kooky kind of gravitas. You get the feeling their junior high school teachers would have labelled them 'precocious' in public. In private, over coffee in the staff mess room, something rather different.

Their relationship is what drives Girlpool, and on their debut proper it produced a few moments that were genuinely breathtaking. The set-up for that record was as old as time: guitar, bass, two vocals and a handful of overdubs. The result recalled the heady, shit-grinning genius of Violent Femmes or the Moldy Peaches; songs about lives you can't be part of, except by listening to two girls singing for three minutes over four chords. Songs talking about kids you've never met, doing things that sound, well... kind of cool.

Well, as Primus asked, 'Is It Luck?' Where do you go after pulling a giant, beaming rabbit out of your hat? In this case the answer is a few steps backwards.

It all starts encouragingly. '123' and 'Corner Store' are Kimya Dawson-inflected romps that use the most obvious new factor - a full drum kit - that was missing from their debut to drive their usual twin harmonies along jauntily enough. Missing, but not missed. The most transcendent moments from their first record relied on the lo fi-ness of the enterprise - the sense that this was two artists, almost one mind in two bodies, staring down the audience. With their pop melodies more smoothly defined, and the whole thing tied to the regular rise and fall of percussive accompaniment, something is lost. 'Fast Dust' is one track that genuinely benefits from its smattering of percussion. Yoni Wolf would be proud to call this one his own. It is utterly gorgeous. ‘Sleepless’ also pounds along very satisfyingly.

But the inclusion of drums throughout muddies the mix and delays the message. It’s one thing to build on a successful formula, and quite another to undermine it. Girlpool, perhaps by seeking to develop their live sound towards a more mainstream delivery, have lost more than a little shine. Many people will, like me, have missed out the first time Girlpool came around. Powerplant is not the strongest record they'll release, but neither, you'd imagine, will it be their last. There's more than enough here to suggest that we may still be in the earlier days of a long and beautiful friendship.