Signal Path

When we set out to create Roon, we felt very strongly that users should have access to honest and precise information describing how their software and hardware devices are performing audio playback. We also felt that great audio hardware should be showcased. As such, whenever Roon is playing to a Roon Ready device or a recognizeable Roon Tested device, we include branding, artwork, and product manual links. Our ability to support specific hardware devices is deeply related to whether or not we can lay hands on it during development, QA, and when addressing support incidents.

It is very easy for poor system design, or poorly implemented or misplaced DSP to ruin an otherwise excellent experience, and too often, software, hardware, and operating systems silently modify the audio stream without providing any feedback. While it's impossible for us to identify every processing step that is performed on an audio stream, particularly after we've handed it off to a hardware device, we are committed to transparency and make an effort to paint a clear picture at all times.

How to Find the Signal Path

In the footer, at the bottom of the screen, there is a little colored light – it might be yellow, green, light blue or bright purple. Click that thing. It should pop up a little depiction of the path that the audio is taking. If you are playing to a hardware device that Roon recognizes, you will also see some information about that product.

Interpreting Signal Path

Roon uses four colors to predict the sound quality, read on to see what each color means in context. 

Lossless Signal Path Example

Lossless signal paths are indicated by a bright purple light, and mean exactly what the name implies: that the stream is going from the file to the device without being modified. Lossless signal paths are pretty boring--there just isn't much to look at if no-one's touching the audio stream. This is one of the more interesting ones possible in Roon, because it identifies two separate devices that are involved in the playback chain.

Enhanced Signal Path Example

Enhanced signal paths are indicated by a bright blue light. This means that Roon is performing some signal processing steps on the audio because you asked for them. The most common reason for a blue light is that features like Volume Leveling or DSP Engine are in use. This is an example of an "enhanced" signal path, in this case because upsampling is configured in DSP Engine.

High Quality Signal Path Examples

You can identify a high quality signal path by looking for the green light.

OS Mixer Output

While the Mac software mixer does not do anything too gross, it might be performing software-based volume adjustments or sample rate conversion before playing the audio. As such, we can't guarantee that the output quality is lossless, so we label it as "High Quality".

Conversions for Compatibility

In this example, DSD64 audio is being converted to 24bit/88.2kHz audio because that is the resolution and format that is supported by the connected AudioQuest Dragonfly. This is an extremely high-quality conversion, with virtually no audible loss in fidelity, but it wouldn't be right to portray it as "lossless".

DSP Volume

Enabling DSP volume inserts processing steps into the playback change that interfere with lossless playback. There's nothing wrong with this: Features like this also bring great value! We are just trying to keep things honest. 

Low Quality Signal Path Example

This is a low quality signal path – you can tell because of the yellow light. In this case, we've labeled it as low quality because the source material is an MP3 file. For the most part, if you see a yellow light, it's because a lossy file was involved.

Notes on Device Branding

We try as hard as possible to identify devices one-by-one in Signal Path, but sometimes it just isn't possible. There are several reasons why your device may not show up here:

1. If we don't have the device in-house, or we don't know how to recognize it, it won't show up. Encourage your manufacturer to contact us!
   
2. Many devices that don't have unique driver strings or USB IDs--often these will be named something like "Manufacturer USB Audio" instead of "Manufacturer Product".
   
3. Some devices use generic drivers (for example, Thesycon drivers). These can't be pinned down to a particular manufacturer.
   
4. ASIO-based drivers do not provide a facility for device identification.

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