More than most, Jason Amm's work as Solvent embodies the original ethos of "synth-pop": that is, hook-laden music built lovingly out of the buzz and hum of analogue synthesizers. Solvent's newest full-length on Ghostly International—his first in nearly six years—is called Subject to Shift, and its title reflects the changing tone of Amm's music. On Subject to Shift, the "cute, happy robots" of 2004's Apples & Synthesizers are few and far between, and in their place is a mix of dystopian, acid-tinged futurism and bittersweet romantic ache.

While Solvent's brightly hued synth tones are still very much in effect on Subject to Shift, Amm's sound has grown deeper and more burnished, hinting at darker conceits and moods than on previous records while laying their creator's emotions bare. "Formulate"'s micro-disco throb and slippery, vocoder'd lead hint at Amm's earlier dancefloor leanings in menacing style; and "Don't Forget to Phone" wraps a bevy of dark vocal hooks around a jaunty schaffel beat, evoking the paranoia and conflicted feelings inherent to every break-up; while "Caught a Glimpse" and lead single "Loss for Words" display two different shades of Solvent's love affair with technology-aided melancholy, recasting new-romantic tropes in a machine-only context. Unlike his previous releases, Subject to Shift is full of Amm's vocals, which have only grown more confident (and, in many cases, vocoder-free) with time.

To say that Solvent is "back" would be a misnomer—Jason Amm has been with us all along, steadily producing new material, nudging the Solvent sound towards something grander and more rewarding than anything he's previously produced. Laced with live vocals and dripping with Amm's blood, sweat, and tears, Subject to Shift is machine-made but palpably, beautifully human.