Mac HDMI Audio Volume Control: How to Control Individual Apps with External Monitor

The Mac HDMI Audio Control Problem

Connecting your Mac to an external monitor via HDMI should be simple — plug it in and enjoy your bigger screen. But then you discover something frustrating: your Mac's volume controls either stop working entirely or only control the system volume, leaving you unable to adjust individual apps.

This creates a common scenario: your music is blasting through the monitor speakers while you're trying to have a quiet Zoom call, or Chrome's notification sounds are drowning out your Spotify playlist. Unlike Windows, which has had per-app volume control since Vista, macOS treats HDMI audio as an all-or-nothing affair.

Why Mac Volume Control Gets Weird with HDMI

When you connect an HDMI monitor, macOS automatically routes all audio to the external display. This often disables your Mac's built-in volume controls because the system assumes the monitor or TV will handle volume adjustment.

Here's what typically happens:

• System volume controls become greyed out
• All apps play through the same audio output
• No way to adjust individual app volumes
• Monitor speakers often lack fine volume control

This design made sense when Macs were primarily single-display machines, but it breaks down in today's multi-monitor workflows where you might want different apps playing through different outputs.

Method 1: Check Your Audio Output Settings

Before diving into third-party solutions, verify your Mac is routing audio correctly:

1. Open System Preferences → Sound → Output
2. Select your HDMI output from the list of available devices
3. Test the volume slider — if it's greyed out, the monitor is controlling volume
4. Try holding Shift + Volume keys to access fine volume control

If the volume slider works, you have basic system-wide control. But this still doesn't solve the per-app volume problem.

Method 2: Use Audio MIDI Setup

Mac's built-in Audio MIDI Setup can create aggregate devices, but it's complex and doesn't provide per-app control:

1. Open Audio MIDI Setup (Applications → Utilities)
2. Click the "+" button and select "Create Aggregate Device"
3. Check both your built-in output and HDMI output
4. Set this as your default output in System Preferences

This creates a combined output that plays through both sources simultaneously — useful for some scenarios but not for routing specific apps to specific outputs.

Method 3: Third-Party Audio Routing Solutions

For real per-app HDMI audio control, you need dedicated software. Here's how the main options compare:

SoundSource ($49) offers comprehensive audio routing with a 10-band EQ and Audio Unit plugin support. It's the most feature-rich option but expensive for basic volume mixing.

Sound Control (~$29) provides per-app volume control but lacks some advanced routing features.

Soundish takes a different approach — focusing specifically on the core features Mac users actually need: per-app volume control (0-200%), per-app output routing, and the ability to mute individual apps. You can route Spotify to your speakers while sending Discord to your HDMI monitor, each with independent volume control.

Setting Up Per-App HDMI Audio Control

Once you have audio routing software installed, here's the typical workflow:

1. Install and launch your chosen audio control app
2. Grant necessary permissions (usually Core Audio access)
3. Select your HDMI output as one of the available destinations
4. Route specific apps to your HDMI monitor:
   • Video calls (Zoom, Teams) to monitor speakers
   • Music apps to your main speakers or headphones
   • Browser audio to whichever output makes sense
5. Adjust individual volumes for each app independently

Pro Tips for HDMI Audio Management

Create audio profiles for different scenarios. When you're in work mode, route communication apps to your monitor and keep music on headphones. For entertainment, send everything to the monitor's speakers.

Use volume overdrive carefully. Some apps allow boosting audio beyond 100% — useful for quiet videos but can cause distortion or hearing damage.

Consider your monitor's audio quality. Many external monitors have mediocre speakers. You might prefer routing only certain types of audio (like system notifications) to the monitor while keeping music and calls on better audio devices.

When HDMI Audio Control Becomes Essential

Per-app HDMI audio control transforms from "nice to have" to "absolutely essential" in several scenarios:

• Remote work setups where you need calls through one output and focus music through another
• Content creation where you're monitoring different audio sources
• Gaming where you want Discord chat separate from game audio
• Shared spaces where some audio should stay private (headphones) while other sounds can be public (monitor speakers)

The Bottom Line

Mac's approach to HDMI audio control works fine for basic use cases, but falls apart when you need granular control over individual apps. While workarounds exist using built-in tools, dedicated audio routing software provides the clean, reliable solution that matches what Windows users have enjoyed for years.

The key is choosing software that matches your needs — whether that's a full-featured professional solution or a focused tool that just handles the core per-app volume control that macOS should have included from the start.

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Originally published at appish.app