SPL (Sound Performance Lab) is a German pro-audio manufacturer founded in 1984 by Hermann Gier, a recording engineer and music producer. Based in Niederkrüchten in the lower Rhineland region of Germany, the company designs and builds hardware for music production, mastering, film post-production, broadcast, and high-end hi-fi. Every product is developed and assembled at SPL's own facility under the operating entity SPL electronics GmbH.

The brand is closely associated with its proprietary 120V audio rail technology (VOLTAiR), which runs internal circuitry at significantly higher operating voltages than conventional analog designs for increased headroom and dynamic range. Signature products include the Transient Designer for shaping attack and sustain, the Vitalizer psychoacoustic processor, the PASSEQ passive mastering equalizer, the IRON mastering compressor, and the Phonitor headphone amplifier with its Matrix crossfeed circuit. SPL's catalog spans mastering-grade outboard (DMC console, MC16 monitor controller, Hermes, Gemini M/S processor), studio channel strips (Channel One, Track One), and a Professional Fidelity line aimed at audiophile listening.

SPL hardware has a strong following among mixing and mastering engineers who favor analog outboard, and its units are found in commercial studios worldwide. The Transient Designer in particular has become a staple tool for drum and dynamic shaping.

SPL has 105 products cataloged on Equipboard, including Effects Processors, Preamps, and Studio Monitor Management. Their gear is featured by 82 artists, with the strongest followings in Electronic, Rock, and Pop. Notable users include Ben Frost, Jaycen Joshua, and Colt Capperrune. Most SPL products sit firmly in the high-end, boutique range.