If there was a way to define the sound of Mountains, the recording moniker of duo Koen Holtkamp and Brendon Anderegg, it's to call it expansive. Nowhere is this clearer than on their 2008 album, re-issued this year as a limited edition of 1,000 copies, Mountains Mountains Mountains. Over the course of four tracks Mountains create soundscapes and experimental compositions that are truly breathtaking. Songs build slowly and sounds are layered in a way that allows them to compliment one another - not once does it feel as though the separate elements are jostling for your attention.

Mountains combine both electronic and acoustic instrumentation to create the basis of their pieces and then utilise repetition and variation to craft the intricacies of the songs. On second track 'Nest' a plucked Spanish guitar is married with samples of radio chatter and static as well as what sounds like the wash of waves. These sounds fade in and out of audible range allowing the ear to briefly catch the sound before it is lost again, meanwhile the guitar is plucked at a steady rhythm, the pattern of notes changing subtly as the song goes on. The volume of the mix also seems to be shifted down slightly, as though Holtkamp and Anderegg want you to listen in more closely and train your ear to detect all of the rich wonders they have produced. If ever there was an album purely for headphone listening, then this is it.

Closing track, 'Hive' is in some respects the antithesis of 'Nest'. Again a guitar becomes the focus of the song, but here it is fed through so many effects that they eventually distort completely to static noise. Unlike the other songs on the album, the subtlety is not in the progression from one state to another - after almost three minutes of shimmering, reverberated guitars, the sound fades away and is replaced by a wall of abrasive noise. It's like a sudden movement deep within the earth, a roaring, almost menacing noise created out heavy overdrive and feedback. It's heavier and louder than anything put out by a rock band, it is the kind of sound that Kevin Shields or Godspeed You! Black Emperor strive to achieve. And yet, within the drone there are details to be found. The strummed guitar rhythm from the start of the track is just audible, calling out from the static like a radio transmission being discovered.

In many ways 'Hive' sums up this re-issue of Mountains Mountains Mountains. The original release was limited to 500 copies and was the band's first release outside of their own label. As their popularity has grown in recent years, and along with the release of new album Centralia this year, it is now the perfect time to discover the band's origins in recording and releasing music. Speaking about the album's legacy for the duo, Holtkamp remarked that "while these pieces are clearly more minimal and intimate on some level and our technical approach has changed somewhat, the dynamics between the acoustic and electronic elements remain fairly consistent throughout our releases."

Intimacy is something that is often lacking in experimental and ambient records, but it is certainly found here. The album's opening track 'The Whale Years' was recorded during an improvised session one night during their first US tour. It starts quietly, with the volume not really picking up until the 8 minute mark. This track is however rich in detail. Under the main melodic build-up there is all manner of sounds - clicks, electronic beeps, waves and even a violin. It's calming and a fantastic introduction to the album and the band. It's true that their most recent albums have grown more complex, but the simplicity of this record is not in any way a negative. It in fact makes it easier to find yourself lost in the sounds created by Holtkamp and Anderegg. Five years on Mountains Mountains Mountains stands up as an accomplished and arresting record.