Delta Blind

Delta Blind is a loudness-matched A/B comparison tool for audio engineers.

Feed two versions of the same audio (a mix revision, a reference master, a before/after) into Delta Blind's main input and sidechain, pick A or B to hear it, and toggle MATCH on: B gets continuously (slow-adapting) gain-trimmed to meet A's level, so a preference between the two reflects a real difference, not just "louder sounds better" — the same bias a real blind listening test removes, hence the name.

Built-in test signal included (B is a fixed +7dB louder than A, same tone), so you can hear MATCH working immediately without routing real audio.

Free during the public beta.

Features:

Sidechain-based dual input: main = source A, sidechain = source B.

One-click A/B switching with a short click-free crossfade.

MATCH toggle: slow-adapting gain correction keeps B's long-term level matched to A's.

Live dB readouts for both sources, plus the gain currently being applied to B.

Offline file-comparison mode: load two audio files and loop through the same matching pipeline as live audio.

VST3 / AU / Standalone, macOS (Universal) + Windows.