What Is A Virtual Audio Device?

The Problem It Solves

Operating systems keep applications apart on purpose. Spotify cannot read what your browser is playing, and your browser cannot read Spotify. That isolation is good for security and it is completely unremarkable until the day you want to put a processor between an app and your ears.

That is the day you discover there is no obvious place to put one. Hearing correction has to happen after the music leaves the player and before it reaches your ears, and the operating system does not offer a slot there.

A virtual audio device creates one. It is a software audio path that shows up in your system as an output on one side and an input on the other. Anything written into it can be read back out by another application, which turns two isolated programs into a chain.

The Four Conditions

Every routed setup, on every operating system, with every music app, comes down to these four things being true at once. If all four are true it works. If one is false it does not, and knowing which one is false is most of the work of fixing it.

1. A virtual audio device is installed. It appears in your system’s list of sound devices.
2. Your music is being sent to it. Either the whole system output points at it, or the individual app does.
3. ARIA ONE is set to read from it and play to you. Input is the virtual device, output is whatever you listen through, headphones or speakers. Getting these backwards is the most common mistake and it fails silently.
4. Everything in the chain runs at the same sample rate. The virtual device, ARIA ONE, and the output you listen through all have their own setting, and they have to agree.

Which One Should You Install

Any virtual audio device you trust will work. It does not have to be ours. It needs to run in stereo, support the sample rate you listen at, and show up in ARIA ONE’s device list. Beyond that they are interchangeable, and there is no sound quality difference between them, because none of them change the audio.

On macOS, BlackHole is free, open source, and the most widely used. Rogue Amoeba’s Loopback is paid and adds a visual routing editor, which is worth it if you expect to build more complicated chains. ARIA-Audio-VAD ships with our ARIA Studio installer and works the same way.

On Windows, VB-Audio’s Hi-Fi Cable and VB-Cable are the established free options. Hi-Fi Cable is the one to pick for music, because it handles higher sample rates.

Install it, then restart any audio application that was already open. Applications build their device list when they launch, so a virtual device installed afterwards is invisible until they restart. This accounts for a surprising share of "it did not appear" reports.

Whole System Or One App

There are two ways to feed the virtual device, and the right one depends on what you want corrected.

System output sends everything through the chain. One setting, and every sound on the machine is corrected. The cost is that every sound is corrected, including notifications, alerts, and meeting audio, and if ARIA ONE is not running you have no sound at all until you switch back.

Per-application output routes only the app you care about and leaves the rest of the system on your normal device. Some music apps have their own output selector built in, which is the cleanest version of this. Windows can also assign an output per app from its volume mixer, and on macOS a utility such as SoundSource can do the same thing.

For listening to music, per-app routing is almost always the better choice. It means your music is corrected and your video calls are not, which is usually exactly what you want.

Sample Rate Is Where It Goes Wrong

Of the four conditions, the fourth causes the most trouble, because nothing warns you when it is violated. The symptoms look like broken software rather than a settings mismatch: clicks, crackles, stuttering, audio at the wrong pitch or speed, or silence.

Pick one rate and use it everywhere you can set one. 44.1 kHz and 48 kHz are both safe choices. 44.1 kHz is what almost all streamed music is delivered at, so it avoids an unnecessary conversion.

The complication comes from hi-res services, which change sample rate from track to track. A chain built around a fixed-rate virtual device cannot follow that, so either lock the app to one output rate, or set the virtual device to the highest rate you expect and let the app convert up to it. Both are fine. What is not fine is leaving it to chance and wondering why some albums click.

Why This Is Not Just An Equalizer

It is a reasonable question at this point: your music app already has an equalizer, so why go to this trouble?

Because an equalizer is a shape you choose and hearing correction is a shape that gets measured. The correction ARIA ONE applies is built from your own thresholds across 37 frequencies, which is information no preset has and no slider can guess. Read more on what separates hearing correction from sound personalization.

The other reason is reach. An equalizer inside one app corrects that app. A processor in the audio path corrects everything you route into it, which is the entire point of doing the routing once.

When It Is Not Working

Summary

A virtual audio device is a software audio path that lets one application hand its output to another, which is what makes it possible to put hearing correction between your music and your ears. Install one, send your music into it, set ARIA ONE to read from it and play to your headphones or speakers, and keep every device in that chain at the same sample rate. Set it up once and every application on the machine can use it.