Halfway through Stefan Prins's Mirror Box Extensions (2015) a guy next to me stretches out his arms to hold up an iPad. I've noticed his fiddling with the gadget throughout the performance, lacking the courage to tell him just how distracting it is. As other iPads emerge in the crowd, all of them making noises and projecting tiny details from the stage, I realize I've been tricked. I never figured he was simply following Prins's instructions and was actually participating in this work that focuses on blurring the borders between the virtual and the real.

I should have known better, of course. This year at SPOR Festival, held annually in Aarhus, Denmark, the theme is ‘What You See Is (Not) What You Get’, an open invitation to tricksters from all around the world. With Belgian illusionists Nadar Ensemble acting as guest curators, the focus is on audio-visual works, and their inclusion of Mirror Box Extensions in the ensemble's only concert at the festival was, in hindsight, a harbinger of illusions on display.

Video was also a key element in this concert's second piece, Bluff (2015), a co-production between German composer Michael Beil and French-German director Thierry Bruehl. Intent on deconstructing the elements of music, Beil and Bruehl present a theatrical piece which begins with the Nadar musicians entering the stage looking confused and alienated. At times they play on their instruments – rigorously repeating an atonal fragment until the music becomes just one more prop on stage – and at times they run around in circles as if warming up for gym class. Above them are two large screens on which are projected a series of manipulated videos of the eight musicians, seemingly having something to do with their regular disappearances behind a red curtain to their left. ‘We've encountered some technical difficulties’, the trombonist tells the audience several times, staring conspiratorially at us from mid-stage. They haven't, of course, it's all glitch and tricks, and at one point the red curtain is pulled aside to reveal a photo booth, a gesture somewhat like a magician revealing his secrets.

Outside the concert hall, Belgian director Nicolas Provost's Plot Point film trilogy (2007) is showing, a fascinating tribute to anti-plot. Perhaps a Christopher Nolan movie might have better reflected the widespread will at SPOR Festival to capture the listeners’ attention with surprising visuals and sudden twists. The Nadar concert definitely makes me wonder if there is some kind of coup going on in the world of new music; as yet I'm not quite sure who is usurping whom or what, but I'm pretty sure the revolution is to be televised.

This year's edition of SPOR Festival is the one with the biggest focus on performance and video we've seen so far. Ensemble asamisimasa begins Trond Reinholdtsen's Music As Emotion (2007/16), only to see the composer ‘interrupt’ the ensemble after ten seconds of music, taking to the stage to give a lecture on music and emotions, testing the audience's ability to interpret correctly the emotional content of different excerpts from Tristan und Isolde. And at one point, he clears the stage in order to show a film of himself asking a psychologist if his presence might perhaps be overshadowing the music. ‘People might find that annoying’, she tells him. (The audience laughs.) ‘Ah, my favourite emotion’, Reinholdtsen replies. (Even bigger laughs.) It is, in fact, annoying: after all, doesn't this kind of irony and distancing feel a bit dated?

Unfortunately, the audio-visual dominance seems to inspire a few composers to accompany traditional musical works with unnecessary video footage. Danish composer Niels Rønsholdt's Songs of Doubt (2015) – a collection of ten songs that display a self-consciously awkward sincerity, in a musical language balancing between pop and new music – is performed by the Dutch choir Studium Chorale, an ondes martenot player and two vocal soloists. Here, as at its world premiere at November Music in Holland last year, Songs of Doubt receives the biggest applause of all works, which is interesting because it is its poppish sincerity which sets it apart at new music festivals. It hardly seems necessary though to accompany the performance with huge, black-and-white footage of Rønsholdt having liquids poured on his naked torso (seemingly shot according to the aesthetics of underwear advertising).

The same goes for another Danish composer, Nicolai Worsaae. In his Saariahoesque Squawk (2016), for string quartet, video and electronics, the four string players of SCENATET are hidden behind a screen projecting not only archival footage from the Apollo moon landing but also a live stream of their hidden performance, the two videos threatening to steal focus from the actual musical composition. In other works featured in SCENATET's performance, the relationship between music and video is much more integrated. In Alexander Schubert's Hello (2014), for instance, the composer appears in a video above the musicians in frantic, pre-produced sequences, ordering them about. The chaotic impulse is fascinating, and he also doesn't shy away from Nolan-style 180 degree turnarounds: the piece ends with footage of Schubert editing the video we're watching, which at one point even fades to black, forcing the music to fade too, then appearing once again, discussing with himself how to end the piece. Hello is an example of musical illusionism that leaves the audience mesmerised without lacking compositional substance.

So, in what direction does the rabbit leap once it's out of the hat? In quite a few performances at SPOR Festival it seems to be a bit lost. Austrian composer Eva Reiter's Alle Verbindungen gelten nur jetzt (2008), for cello, electric guitar and percussion, and performed here by SCENATET, presents something akin to a spaced-out Hendrix jam. Americans Jessie Marino and Natacha Diels give an improvised, late-night duo performance which seems to be a celebration of early childhood, the two performers producing random sounds from toy instruments and making peek-a-boo gestures; this almost happy-go-lucky approach is also present in the new works receiving their first performances, Marino's The Whale Is a Capital Fish (2016) and Diels's 35 Degrees (2016). As I found with the musical aspect of the Nadar concert, neither of these really sticks in the mind. A lot of audio-visual works operate within the framework of composed chaos, but it's not always easy to control such strong forces.

Amidst this parade of tricksters unleashing the beast, I do notice some promising composers able to cope with such chaos, though. Wild rabbits are gracefully controlled in Austrian composer Matthias Kranebitter's Dead Girl (Requiem E), a piece from 2008 which combines a faltering electronic backing track of erroneous blips, the toneless flapping of an over-loose double-bass string and a drum machine with the screams of a flute and mechanical hesitations of an electric guitar. Likewise, Hungarian composer Mirela Ivičevič shows great promise with her 2014 piece The F SonG (dominosa VII). The two pieces are performed by musicians from the Black Page Orchestra and Another Contemporary Music Ensemble, but it is perhaps the premiere of Lithuanian composer Vitalija Glovackyte's Virtual Love (2016) that really seems to touch the audience. It's a tale of a long-bearded programmer sitting behind a tiny Casio keyboard, somehow producing the virtual existence of a girl on a screen next to him, kept in nostalgic black-and-white courtesy of an old slide projector. Musically, the piece is as simple as the programmer's beeps and soft new-age synth until, in the end, the code we've seen him hammering into the toneless keyboard slowly seems to make its way into the music as a light layer of random melody. The innocence is welcome at a festival dominated by works moving at frenetic paces.

Other notable premieres include Jeppe Ernst's silent pieces, Etudes (Book II), for between one and six performers, all ‘playing’ on their facial muscles only: they blink, they stare, they act surprised in precise rhythms in front of a singular listener in a dark room, each performer lighting up his own face with a torch. Also, we heard some tech-infatuated premieres in the form of Rama Gottfried's Apophänie (2016) and Leo Hoffman's The Reply (2016): the first using advanced computer analysis to map the microscopic details, captured on live-streaming video, of a partly hidden miniature theatre including, amongst other things, bubble wrap(!); in the latter, we see Hoffman himself standing next to a screen of Venetian blinds, trying to copy the moves from a projected video of what appears to be himself but actually is a female that looks just like him. Both impressive works, but with more invested in the video part than the accompanying electronic beeps.

I'm not really inclined either to oppose or side with the tricksters at this year's SPOR Festival. There is some mileage to be had from comparing composers with magicians: sometimes the audio-visual works touch on the sublime; at other times, the illusions exist at the expense of musical substance. Not all works were equally memorable, I'll put it that way. Once music is reduced to a prop in a visual magic show, the charm wears off more quickly than if you actually hear the will of a composer somewhere inside the performance; otherwise, you find yourself lying on your rubber mattress in your discount hotel room counting magic rabbits and wondering what happened to them.