Recently my 160GB iPod Classic started to die. The battery wouldn’t hold a charge, especially not in cold weather. If I selected an artist/album to listen to, then decided to scroll through and find a different artist/album to listen to, half the time it would simply shut down on me, declaring that the battery was totally empty and I needed to connect it to a power source. And since Apple stopped making the iPod Classic in 2016, it was going to be a real challenge to get a new battery for the thing. Ultimately, I wound up with the Sony NW-A45 Walkman, which I endorse 100%. The sound quality is excellent (it supports virtually any file format you can think of), and the music is accessed via a microSD card, not an internal hard drive. Mine only has 16GB of storage, but I’m using a 200GB microSD card, so I have more music available than I did before. And it costs about half as much as an iPod Touch, the last model Apple still makes.

Anyway, the only artist filed under Classical in my new Walkman is Anna Thorvaldsdottir. I’ve returned to her albums Aerial and In the Light of Air over and over since discovering them in 2015 (and writing about them here). Now she’s got a new release, AEQUA, which expands her music’s sonic range while remaining true to the language she’s developed over three prior releases and multiple compositions for various ensembles.

AEQUA is a collection of chamber pieces for groups of diverse sizes, orbiting the longest and largest work, “Aequilibria,” which requires twelve musicians. All the players are part of the 35-member International Contemporary Ensemble (ICE). It begins with a solo piano piece, “Scape,” which is followed by “Spectra,” one of two works for string trio (violin, viola and cello). “Sequences,” which comes after “Aequilibria,” is for bass flute, bass clarinet, baritone saxophone and contrabassoon; “Illumine” calls for three violins, two violas, two cellos and a double bass. “Reflections” is another string trio, and the album’s final piece, “Fields,” features the unorthodox combination of bass clarinet, piano, electric guitar, cello, double bass and percussion.

“Scape,” performed by Cory Smythe, is the oldest composition on AEQUA; it dates back to 2011 and consists of haunted passages punctuated by huge, crashing low-end chords. The piano sounds treated; notes ring out for an impossibly long time, and there are additional creaks, jangles and pings, as Smythe manipulates the strings directly. At the midpoint of the piece, there’s so much reverb it’s like he’s playing from the middle of a storm cloud. On headphones, it’s almost sensory overload.

“Spectra” and “Reflections” are performed by two different string trios, with cellist Michael Nicolas the only constant. “Spectra” features almost Balkan melodies, along with some of the percussive effects Thorvaldsdottir favors, and some bent violin notes from Josh Modney that sound like dolphins singing underwater. “Reflections” seems to combine long drones with a doppler effect; the notes rise and fall as if the players are speeding past in a vehicle, hurling bolts of sound at each other.

“Sequences,” the wind-powered piece, is like being trapped inside a giant animal as it inhales and exhales. Tuba-like rumbles from the lowest-pitched instruments appear, then disappear, in the corners of the sonic field. Bass flute and bass clarinet offer flurries of melody which are swallowed by low-end drones Sunn O))) would envy.

“Aequilibria” features twelve musicians and is just over twelve minutes long. It begins with a kind of coming-to-order; loud drones fly like bombers over the strings and piano as they play short, trilling figures as if warming up. Long tones like layered harmoniums are paired with repetitive phrases from reed instruments, almost recalling Prokofiev. We hear the percussive strikes against the neck of the cello again, and though the piano takes long breaks between appearances, when it does show up it’s like the player has snuck into the room long enough to land a blow or two on the keys, then vanish again.

The production and mixing on AEQUA is frankly breathtaking. The instruments, so often required to go far beyond their traditional roles, rattle and boom, scrape and clatter; the music is swathed in reverb, but always for dramatic, not romantic, effect; and the use of space, be it distance between instruments or the overall immersive quality of each grouping, is mesmerizing. Thorvaldsdottir’s use of sound puts her in the room with composers as disparate, yet linked, as Roscoe Mitchell, Tom Waits, Einstürzende Neubauten, and Autechre, without taking ideas from any of them, or from anyone else that I can identify, though that’s probably due to my own ignorance of modern composition. I don’t think I own speakers that can do this music justice (the physical version comes with a CD and an audio Blu-Ray), so I’m glad to have good enough headphones to make it worth keeping AEQUA (along with Aerial and In the Light of Air) in my Walkman.