Sigur Rós are currently on tour for the first time in five years, with keyboard player Kjartan Sveinsson back in the fold after leaving in 2012 to pursue other projects, and attracting reviews such as, “Sigur Rós has a way of destroying you and rebuilding you all at once…. I’m reminded of just how powerful music is.”

In this 20th anniversary year, the tour set list features six songs from their iconic third album – known as Untitled but more commonly referred to as ( ) because of its artwork – including the lengthy and thunderous finale “Untitled #8,” which has also closed every Sigur Rós show since it was written in 2000. That’s a greater number of songs than from any of their other six albums, a testament to the album’s importance to the band – which is matched by their fans’ fervour.

( ) was born during a period of great exploration for the band but also expectation, after Sigur Rós’ preceding album Ágætis byrjun, released in 1999, had won America’s inaugural Shortlist Prize for Artistic Achievement in Music, and been proclaimed “The last great record of the 20th century,” by Q Magazine. After going on tour with Sigur Rós’ new number-one fans Radiohead and having three of their songs featured in the Tom Cruise-fronted movie Vanilla Sky, the spotlight was bearing down. Media interest was less focussed on their luminous post-rock-meets- post-classical sound than trying to analyse what emotions and ideas lay behind the band’s curtain of sound – which Sigur Rós themselves has no interest in revealing in any case, said Kjartan.

So, what did the band do next? After building their own studio in former swimming pool in Álafoss, Mosfellsbær, a small rural town outside of Reykjavík, and reuniting with Ágætis byrjun’s British producer Ken Thomas, the quartet – Georg Holm (bass, keyboards, glockenspiel), Jón Þór ‘Jónsi’ Birgisson (vocals, guitar, keyboards), Kjartan Sveinsson (keyboards, guitar) and Orri Páll Dýrason (drums, keyboards) – released an album without an official title, or even song titles.

Nor were there decipherable lyrics. Instead, Jónsi sang entirely in his invented ‘language’ of Vonlenska (in English, Hopelandic), which resembles the phonology of Icelandic with no semantic meaning. The band’s website featured an interactive option where fans could send in their own lyrics; a computer program recognised the most common words and phrases to create an alternative source of words.

No compromise, then, and no insights either, except for the band’s willingness to allow the music to do the talking.

( ) lasted a mighty 71 minutes too, over just eight tracks; the closing two pair spanned almost 25 minutes. The first side was comparatively gentle and simmering; side two was a darker, harder, starker brand of slow burn. But overall, the mood was somehow more majestic and still more intimate than before. The euphoria that had fired parts of Ágætis byrjun – as well as Jónsi’s guitar, often played with a cello bow – was used much more sparingly: there were no drums on two tracks.

“We didn’t want to put titles on the record just because there are supposed to be titles on the record,” said Kjartan. “Besides, when I refer songs to my friends, I always say ‘Check out track five,’ or whatever.”

“It’s pretty fun confusing people with having no titles on this album,” said Jónsi. “The listener just names the song based on what he or she hears. We have our own names for the songs, but we probably interpret them in a different way than other people.

Sigur Rós’s breakout album, Ágætis byrjun, was judged the “last great record of the 20th century” by Q magazine, and soon their music achieved a level of ubiquity in film and TV sync quite out of keeping for a band performing 10 minutes songs in a made- up language.

“We really loved the responses to Ágætis byrjun, we got all kinds of interpretations from people who didn’t understand Icelandic and thought we were saying other things and it turned out these people were interpreting the songs based on their own lives and atmospheres, which was very precious for us,” Jónsi added. “This is partly the reason why we decided to give people the chance to write their own lyrics in the booklet… it’s not the singer telling stories, it’s sort of a soundtrack for each person’s life, so they can write lyrics for their own lives.”

And that whilst some reviewers were bewildered by the lack of titles and words, most were bewitched. For example, “A masterpiece of bombed orchestral elegance, at once expansive and intense” (Q). “The band steer their ghost ship into darker waters, erecting a vast, austere cathedral of sound, then sticking around to score a funeral mass inside” (Spin).”Sigur Rós’ music has all the depth, resonance and humanity of a Brueghel landscape, and is best appreciated at loud volumes in open spaces, as a soundtrack for scenery, real or imagined” (Pitchfork). “As pioneering, unnerving, inspiring, confusing, as lyrically anarchic as everything that has moved the world, ever” (Drowned In Sound).

How did Sigur Rós follow ( )? By collaborating with folk singer Steindór Andersen on a project centred around traditional Icelandic ‘rímur’ poetry; the same team, plus Icelandic legend Hilmar Örn Hilmarsson, then forged the stirring opera Odin’s Raven Magic, centred on a massive stone marimba with choir and orchestra.

The band have now released seven studio albums, two films, solo albums, side projects, orchestral and choral works, tech start-up collaborations, music for dance companies and leading visual artists, as well as several film scores.

Still no compromise, then; no bowing to convention, just allowing the muse to steer the way forward and the music to do the talking. With a new album due in 2023, expect Sigur Rós to continue on the same path.