Audiophile Circuits League is a Berlin-based collective of musicians and engineers founded by Stefan Lewin and Martin Schoenauer, specializing in Eurorack modular synthesizer equipment designed and assembled in Germany. Lewin leads electronic design while Schoenauer handles business operations and component layout, with both an emphasis on discrete analog circuitry and high audio fidelity.

ACL's catalog spans oscillators, filters, envelopes, LFOs, mixers, utilities, power supplies, and complete cased systems. Notable modules include the Sinfonion harmonic sequencer, the Discrete Core Ladder VCF (a Moog-inspired filter), the Dual State Variable VCF, the Envelope X3 (based on the Roland System 100M), the WT-QUAD-LFO wavetable LFO, the VC Dual Delay, the PAN MIX stereo panning mixer, the M/S Matrix, and a pro-grade Audio Interface module. The company also sells its System 1, a 6U/84HP Eurorack case populated with its stereo modules.

The brand is recognized within the modular synthesis community for technically ambitious designs, hand-assembled build quality, and a stereo-oriented approach to module architecture.

Audiophile Circuits League has 6 products cataloged on Equipboard, including Modular Synthesizers. Their gear is featured by 1 artist, with the strongest followings in Electronic and Pop. Notable users include Andrew Huang.