"Progress is impossible without change." This deceptively simple nugget of wisdom came from a man who knew a thing or two about music and literature, and remains the only person to have won both a Nobel Prize and an Oscar. But the sentiment behind one of George Bernard Shaw's most profound utterances is as true today as it was in the late 19th Century, and one that Sónar 2013 has wholeheartedly embraced. Celebrating its 20th anniversary – a milestone described as "a moment of celebration and, at the same time, a new challenge" by co-founder Enric Palau – the festival, like any adolescent passing into adulthood, decided to move away from home, swapping the cramped yet quirky MACBA and CCCB museum grounds for the cavernous functionality of the Fira Montjüic exhibition halls in Plaza España. In short, it's all grown up, and getting serious about the future.

We're told that officially, capacity has jumped from 12,000 people a day to 15,000, but that seems too high for last year and too low for this. Admittedly, anyone who waited half an hour for a beer, or queued in vain to see Peaking Lights in a delightful converted chapel last year probably revelled in the huge open spaces and easy flow of people, but such scale comes with a price; lack of charm. Spread over a total of four floors and three separate buildings, the intimacy and immediacy that so characterised Sónar Dia is lost in the vastness, the majority of people spending the first few hours peering quizzically at maps or information points. As well as three stages, there's an auditorium, a cinema, and a large, ground floor space split between technology stands and a working area for music "hackathons". There are even proper bathrooms with – wait for it – working soap dispensers and hand dryers.

  • AlunaGeorge

Part of Sónar's appeal has always been its diversity, mixing household names with the avant-garde, and this year is no exception. Wandering around and dipping in and out of sets has always been the best way to get a feel for the scope of the program, especially during the first few hours before the more recognisable acts are due on stage. However, the flip side of this bargain is that a midday start and the weather – cloudless, azure blue skies and a balmy 27 degrees – are not exactly geared towards enjoying the experimental sonic assaults that many performers specialise in. Cassegrain are a perfect example; the hypnotic, driving dubby techno of this Greek/German duo is entirely lost on the meagre crowd, many of whom end up sitting down, watching impassively. As impressive as their tightly wound textures are, Alex Tsiridis and Hüseyin Evirgen cut two lonely figures bobbing away in a dark, throbbing sea forlornly beckoning – with little success – others to join in.

The same fate befalls EVOL, whose thirty minute exploration of the "poing" sound – basically one effect, chewed, warped, and played at various speeds – sees everyone rooted to the ground, gawping with a mixture of wonder and puzzlement. Blasts of strobe in time with the "music", the only light effect they use, give the sensation of being stuck in a particularly repetitive, low-budget computer game. It's a brave, perhaps symbolic set, but the ennui that sets in remains until swept away by the heavy, pulsating force that is Liars. Leaning almost exclusively on WIXIW and a smattering of new material, they're a powerful, mesmerising force, stomping through an hour with barely a pause for breath. The sound is stunningly good, as are all the favourites – the title track, 'No.1 Against The Rush', 'Octagon' – but it's the closing double whammy of 'Brats' and a new song dedicated to Daniel Miller, a shimmering hazy drone devoid of drums, purposefully sweeping Angus Andrews' voice along, that finally tips an audience teetering on the brink of euphoria over the edge.

  • Bat For Lashes

As joyous as it is, it also leaves a bittersweet taste thanks to a problem that repeatedly rears its head during our odyssey – timetable clashes. For reasons best known to themselves, and despite Thursday's paucity of must-see moments, the organisers schedule Gold Panda in exactly the same time slot. Wandering out to catch a snippet, we discover a point where you can just about listen to both sets simultaneously, but its no compromise and we scuttle back to the New York trio's foggy embrace. Some avoid this problem by essentially setting up camp in the central square; the swathes of soft astroturf and two massive, overhead canopies providing shade and sanctuary to those happy to witness whomever plays the main stage or DJs between sets, turning the Village into Barcelona's most expensive terrace.

The other days deliver equal highs and lows. The noirish synth-pop of Chromatics is as brilliantly executed as always, a tight, razor-sharp set including the slow-glide funk of 'Lady' alongside both their famous covers, and they're closely followed by hotly tipped London duo AlunaGeorge. For a band yet to release an album, they give a remarkably assured performance, singer Aluna Francis confidently swaggering back and forth while George Reid stabs away at his keys. Their new material sits comfortably alongside the dance-y, futuristic RnB of early singles 'Your Drums, Your Love' and 'You Know You Like It' and, as the sun sets and the beers start to take hold, prompts much dancing and a general, hands-in-the-air euphoria.

  • Chromatics

A huge disappointment is missing out on beatboxer extraordinaire Beardyman, a massive queue and poorly advertised booking system thwarting our attempts to witness the debut of his Beardytron 5000 Mk II – no joke – a mobile recording device which apparently "enables him to travel much further than any beatboxer has gone before". Whilst it sounds a bit Space Odyssey meets Spinal Tap, it's exactly the kind of zany brilliance that one expects from Sónar. Clips of the device in action confirm it would have been anything but boring, and provoke pangs of sadness at our failure to catch a genuine, ground-breaking highlight. The much anticipated performance of Luftbobbler by Dinos Chapman is also a let down; a cold, staid rendering of his admittedly challenging minimalist creations, loops of uninspiring graphics failing to add anything while he pokes away at several MacBook Pros in the shadows and dry ice.

  • Nicolas Jaar

Such disconnect between audience and performer, music and setting, is another issue that silently stalks proceedings. After three days under a burning sun, it's remarkable how little warmth or humanity has been present in the music we've experienced. It's not down to any individual act, but there's precious little counterpoint to the hard, metallic sheen of most material, no real soul. It's all machine tooled, mnml precision, as if hewn from some monolithic, dystopian future. Even the softer, more melodic moments, like the gloriously eerie, haunted electronica of UMA fail to connect; like Jude Law's automaton gigolo in A.I., it's aware of its function but doesn't – seemingly can't – truly understand. There's a lack of the organic, rendered all the more stark by casting our minds back to the spirit and fluency of Austra, Thundercat, and Jesse Boykins III at last year's edition.

Only Mykki Blanco, who delivers a rapturous, no-nonsense set of material culled from his Cosmic Angel mixtape, bucks this trend. Dressed in just shorts, baseball cap, and garish gold chain, he spits his rhymes backed by one DJ and simple beats, sometimes even going a cappella. Strutting, pouting, and sweating profusely, he owns the stage; tales of prejudice and fighting your corner marking him out as a poet laureate for the disenfranchised and put upon. He jumps into the crowd several times and, much to the chagrin of security, invites a stage invasion for closer 'Wavvy', 40-odd revellers scrambling over the barriers to groove away in the spotlight. At the end, he again descends to the masses, by now shrouded in a light fog of hash smoke, and spends a full ten minutes shaking hands, posing for pictures, and being hugged profusely. Gracious, humble, and patient, no request goes unfulfilled, a timely reminder how touching, and inspiring, music can be.

  • Kraftwerk

The transition from Day to Night, from city centre to industrial mega-complex, is not easy, the theme of awkward clashes and run times continuing. Headliners Kraftwerk and the Pet Shop Boys both start at 10.45pm sharp, necessitating a mad dash for the shuttle buses. With upwards of 40,000 descending on the Fira Gran Via – capacity here has also been increased thanks to a reorganisation of space – queues are long and time is tight, meaning we catch less than half of Olafur Arnalds and TNGHT on the Friday and Saturday respectively. It also means we completely miss out on Vatican Shadow, whose furious, intense rap-techno had been marked down as the perfect warm up to a night of raving.

With the increase in capacity comes an increase in spectacle, the Night leg dealing mainly in shock & awe EDM and bowel-shaking low end. The main hall is simply gigantic, an industrial hanger that could easily swallow two jumbo jets creating a scale that most at least attempt to take advantage of. Skrillex, currying local favour by donning a Barça top, takes up residence in the cockpit of a giant, futuristic black spaceship to deliver his trademark Teutonic drops and post-rave party soundtrack. Borrowing a trick from Wayne Coyne, a suited-and-booted Diplo makes excursions out over the crowd in a giant hamster ball, a million-watt LED assault burning retinas to accompany Major Lazer's dancehall dubstep. Only 2 Many DJ's rein in the visual sideshow, relying instead on their ever brilliant, feel-good mashup anthems to move people's feet.

But it's mainly all about those two, larger-than-life names at the top of the bill. Kraftwerk are, unsurprisingly, immense. Much of the music on show, and probably Sónar itself, would likely not exist if Ralf Hütter and Florian Schneider hadn't become so obsessed with technology and audio manipulation in the early 1970's, and yet it's bewildering to think just how modern, how very now they still sound, like music beamed in from some future dimension. Prescient too; in a week that saw Edward Snowden turn whistleblower extraordinaire, the updated lyrics of 'Computer Love' – "Interpol and Deutsche Bank / FBI and Scotland Yard / CIA and KGB / Control the Data and Memory" – perfectly chime with our worries and fears about secret surveillance and privacy. There's also a delicious irony during opener 'The Robots', thousands of smartphones held aloft while "We're charging our battery" and "We're functioning automatik" flash up on the screens.

  • Justice

If there's one criticism, it's that the 3D graphics look somewhat inconsequential to those not lucky enough to find themselves in the front third, a difficult task considering most of the festival appears to have converged on the Club. This isn't a problem the Pet Shop Boys have, their five-part audiovisual spectacular blasting all the way to the back with lasers, strobes, and various projections. Highly theatrical, they draw the eye more than the ear – particularly with their newer material – variously appearing in huge, spiky jackets, mirror ball helmets, and horned, pagan-esque animal skulls. It's slick, brilliantly curated pop opulence, perfectly poised with one foot in their past and the other planted firmly on the dancefloors of the future.

The near two-hour run time of both sucks time and opportunity away from others, and completely dominates each night. Too much so? It's hard to tell. After all, such shows don't come cheap, and if a festival is willing to invest, it's only fair they get their money's worth. On the other hand, watching both means Bat For Lashes, Jurassic 5, and Nicolas Jaar – who last year had to compete with Lana Del Rey – are beyond our schedule, big names in their own right who shouldn't have to compete. We speak to many who are here for just for one night with their heroes, shelling out €75 – half the cost of a full festival pass – for the privilege, and a cynic might conclude that such long sets from established stars, something that's being replicated at other events, is a way to maximise profits and minimise risk.

  • Pet Shop Boys

A quick scan of the timetable also reveals subtle increments in commercialisation. Two Door Cinema Club deliver a magnificent, sugar rush of up-tempo disco indie, but they're the only real "band" to be had; everything else is more a variation on a theme. Clubland bangers, techno overlords, and high octane, N-R-G dance dominate, and after several hours, blends into a kind of omnipresent, sonic mush. In fact, it's easy to wander around and not really see anything, losing yourself instead in isolated moments and drops, chicanery on the dodgem cars, or your own chemical kingdom. Sónar is many things to many people but, first and foremost, has always had a voyage of discovery at its heart. The tagline – "Festival of Advanced Music" – says it all. In an interview with El Periódico, the founders spoke of not wanting to "turn the page and start a new era by breaking everything," but adding that "the idea of change is part of our way of being." It's undoubtedly tough to survive in the current economic climate – no event is too big to fail - but perhaps endless expansion or relying on spectacle over substance is not the answer. "Sónar is a festival of discovery," maintained Palau; they just have to be careful that size and continuing success doesn't translate to bloat, or deprive anyone of the unique experiences that made it so special in the first place.

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