How to send a specific app's audio to an HDMI monitor on Mac

The direct answer: your HDMI monitor shows up as one more output device, and a Mac can only aim the whole system at one device at a time — so pointing sound at the screen drags everything there, not just the program you meant. Getting a single app onto the HDMI display while the rest plays where it was takes a per-app output rule. Some media players expose their own device menu; for everything else, a dedicated router assigns the screen to just that app and leaves the default where you had it. Mind the HDMI quirk too: once the display becomes the output, macOS greys the volume slider and the level keys quit responding, so pick a tool whose per-app level still moves over HDMI.

The setup is common. A big monitor or TV on your desk has its own speakers, and it reached them over HDMI. You want a movie, a game, or a slideshow playing out of that screen while your music, calls, and alerts stay on the desk speakers or the laptop. macOS treats all of that as one stream to one device — so the moment you point audio at the HDMI display, the whole Mac follows it there, and your music lands on the monitor too.

Why the Sound menu sends everything, not one app

On a Mac there's a single active output device at a time. Open System Settings → Sound → Output and your HDMI monitor shows up in the list — usually by its model name — right alongside the built-in speakers and anything else attached. Selecting it works exactly as advertised: audio starts coming out of the screen. The problem is that it works for everything. There's no column for "this app to the HDMI display, that app to the speakers." One list, one choice, applied to every running app at once. That's the same wall you hit with per-app volume in controlling individual app volume on a Mac — macOS simply doesn't expose audio on a per-app basis.

The HDMI catch: your volume slider goes grey

HDMI adds a wrinkle the other outputs don't. Over HDMI and DisplayPort, macOS assumes the display or TV manages its own audio level, so it disables software volume control. The menu-bar slider greys out, and pressing the volume keys shows the no-entry symbol instead of the usual level overlay. You're suddenly stuck reaching for the monitor's physical buttons — which are slow, often buried in an on-screen menu, and control the whole HDMI feed, not one app. So even after you route audio to the screen, adjusting it is a chore. Any real fix for "one app to HDMI" has to solve the volume problem too, not just the routing.

The free path: the app's own output, or BlackHole

Start with the cheapest thing that might already work. A handful of apps carry their own audio-output setting — VLC, some media players, DAWs, and games with an audio-device option in preferences. If yours does, point it straight at your HDMI monitor and set the system output back to your speakers. Nothing to install, and it's an honest, complete fix for that one app.

Most apps — Chrome, Spotify, Slack, most streaming sites, plenty of games, anything Electron — have no output picker at all. For those, the free route is BlackHole, a free, open-source virtual audio device, paired with Audio MIDI Setup. You install BlackHole (a one-line Homebrew install or a signed installer), then build an aggregate or multi-output device and steer the app through it. It works, and audio tinkerers rely on it every day.

The honest catch: BlackHole is built to pass audio between apps and duplicate a stream across outputs, not to hand you a clean "this app to the HDMI screen, everything else to the speakers" switch — so getting exactly one app onto the monitor usually still needs the app's own picker or a chain of aggregate devices you maintain by hand. And you're still fighting the greyed-out HDMI volume, since Audio MIDI Setup doesn't give you a per-app fader. Capable, but fiddly for this specific goal. If you want the general version of this, the guide on sending one app's audio to a different output on Mac walks through the same routing options for any output device.

The gotcha worth knowing: Background Music is volume, not output

Background Music comes up constantly as the free per-app answer, and it's genuinely good — but it does volume, not per-app output. As of 2026 it keeps every app on the same system output device; assigning one app to a different output is a long-standing open feature request, not a shipping capability. So for "send this app to the HDMI monitor but keep music on the speakers," Background Music can set the levels but can't do the actual routing. Worth knowing before you install it for the wrong job.

The set-it-once path: a per-app routing app

A routing app does at the OS level what these apps won't do themselves: it assigns each app an output device independent of the system default. You set the default output to your speakers, add one rule — this app → HDMI monitor — and everything else keeps flowing to the speakers automatically. Because it holds a route per app, it reapplies the HDMI assignment whenever the display reconnects, without you touching the Sound menu. And because these apps ride each app's audio stream directly, per-app volume keeps working even when macOS has greyed out the system slider over HDMI.

SoundSource from Rogue Amoeba is the deep option: it sends individual apps to different outputs, adds effects and EQ, and version 6 (December 2025) expanded output support, including grouped outputs and routing an app to AirPlay devices. It's a one-time $49. Fader does the same per-app output routing in a clean list — pick a device per app and it sticks — for a one-time $19.99, and it also rides per-app volume from your keyboard in the same app, which is exactly what you want when the HDMI slider is locked. Here's how the options stack up for this exact one-app-to-HDMI job.

The exact setup: one app on the HDMI screen, the rest on speakers

With a per-app routing app installed, the recipe is short:

1. Set the default system output to your speakers or laptop — that's where everything plays unless told otherwise. 2. Add one app route: pick the app (the video player, the game, the slideshow) and choose your HDMI monitor as its output. 3. Leave it. Every other app inherits the speakers; the one app you routed plays out of the HDMI screen and returns there whenever the display reconnects. 4. Because the system slider is greyed out over HDMI, ride that app's level with the routing app's own per-app volume rather than the Mac's volume keys.

In Fader that's the Routing tab: the default output sits at the top, and each app route is a row — App → Device — from a dropdown. Because the same app also gives every running app a fader on your keyboard, you can nudge the HDMI app's level with letter keys, sidestepping the locked HDMI slider entirely. One note specific to HDMI: some displays add a little audio latency, so for tight lip-sync in a game a wired or built-in output can be the safer ear — HDMI shines for a movie, a slideshow, or anything playing to the room off the big screen.

Bottom line

macOS points every app at one output, so choosing your HDMI monitor sends the whole Mac there — a clean one-app-to-HDMI split isn't something the Sound menu can do, and HDMI makes it worse by greying out the volume slider once the screen is the output. If your app has its own output picker, use it — free and done. If you like tinkering, BlackHole plus Audio MIDI Setup is capable but fiddly for this, and Background Music won't route output at all. If you'd rather set one rule and move on — this app to the HDMI screen, everything else to the speakers, with a volume control that still works over HDMI — a per-app routing app is the straight path. SoundSource is the deep, $49 option; Fader does the routing plus keyboard-fast per-app volume for $19.99 one-time.