The Art of Audio Alchemy: Transforming Zoom Calls into Studio-Quality Experiences

When the pandemic thrust remote work into the spotlight, Noah Liebman—an audio professional—faced a deceptively complex challenge: How could he use his studio-grade Shure SM57 microphone and guitar pickup seamlessly on Zoom calls without sacrificing audio quality? The answer evolved into a masterclass in audio routing, blending hardware ingenuity with software sorcery. What began as a personal project underscores a universal truth for developers and creatives: In the era of virtual collaboration, controlling your audio stack is not just a luxury—it’s a competitive edge.

The Core Conundrum: Why Simple Solutions Fall Short

Standard video conferencing tools compress and process audio, stripping away nuance crucial for musicians or audio-sensitive workflows. Liebman’s goals were uncompromising:

• Mix multiple inputs (mic, instruments) via a Behringer UMC202HD audio interface.
• Monitor the mix in real-time through headphones.
• Route processed audio to Zoom while hearing call participants clearly.
• Eliminate echo and latency. As Liebman notes, "What a musician really wants" demands more than plug-and-play—it requires bending the system to your will.

Building the Audio Engine: BlackHole and Aggregate Devices

The linchpin? BlackHole, an open-source virtual audio driver enabling flexible channel routing. Liebman deployed two instances:

• BlackHole 2ch: Acts as Zoom’s "microphone," carrying processed output.
• BlackHole 16ch: Serves as Zoom’s "speaker," feeding call audio back into the system.

Aggregate device setup in Audio MIDI Setup, combining hardware and virtual interfaces.

Creating a unified interface required an aggregate device via macOS’s Audio MIDI Setup. This virtualized the Behringer interface and both BlackHole instances into a single 20-channel powerhouse, with the Behringer as the clock source to prevent drift.

DAW as the Control Center: Routing Magic in Reaper

Reaper (Digital Audio Workstation) became the nerve center. Key steps:

1. Input Tracks: Each source (mic, guitar) gets a dedicated track with effects like noise reduction (for HVAC hum) and compression.
2. Master Output: Routes to both headphones (via Behringer) and Zoom (via BlackHole 2ch).
3. Zoom Audio Isolation: A dedicated track ingests far-end audio from BlackHole 16ch (channels 1–2), routing it directly to headphones—not the master—to avoid feedback loops.

Reaper’s device preferences, critical for managing the aggregate interface.

Liebman emphasizes: "What you hear is what the far end hears," thanks to meticulous monitoring. Plugins transform raw input into broadcast-ready audio, a revelation for noise-plagued home offices.

Zoom’s Hidden Gems: Unleashing "Original Sound"

Configuring Zoom was straightforward but pivotal:

• Microphone: BlackHole 2ch
• Speaker: BlackHole 16ch
• Enable "Music and Professional Audio" mode to disable destructive processing like auto-gain and bandwidth limiting. As Liebman warns: "Why use a decent mic if Zoom butchers it?"

Advanced Tactics: System Sound and the Audio Hijack Evolution

For sharing computer audio without Zoom’s limitations, Liebman repurposed BlackHole 16ch channels 3–4. System output routed here, ingested into Reaper via a new track, keeping call audio (channels 1–2) and system sound separate. His 2023 update highlights a shift to Audio Hijack (Rogue Amoeba) for a more intuitive UI—proving the setup’s principles endure even as tools evolve.

Why This Matters Beyond the Hobbyist

This isn’t just about pristine guitar solos in meetings. It’s a blueprint for:

• Developers building real-time audio apps, understanding virtual drivers and low-latency routing.
• Remote Teams demanding high-fidelity communication for design critiques or pair programming.
• Security Implications: Tools like BlackHole expose how OS-level audio routing can be exploited or secured.

In an age where virtual interactions define professionalism, Liebman’s colophon is more than technical showmanship—it’s a manifesto for reclaiming control in a world of digital compromise. As he quips: "Happy calling!" might just mean happier coding, creating, and collaborating.

Source: Telephone colophon: Or, how I overengineered my call audio