Can USB be used to play music?
USB (Universal Serial Bus) is an interface standard for transferring data between devices and computers 1. It was originally designed in the mid 1990s to standardize connections between peripherals and personal computers. Since then, it has become the most common interface for connecting devices to a computer.
USB connections have several advantages over other interfaces like parallel and serial ports. USB supports plug-and-play installation so that devices can be connected and disconnected without rebooting the computer. USB also provides power for low consumption devices so separate power cords are not needed. And USB has greater speeds for transferring data compared to older interfaces.
With its widespread adoption, USB can now be found on all kinds of devices from computers, phones and game consoles to cameras, printers and flash drives. This makes USB a versatile interface for transferring data like pictures, documents, music and more.
What is USB?
USB stands for “Universal Serial Bus”. It is an industry standard protocol that allows for high-speed data exchange and power delivery between electronic devices. As described by the Encyclopedia Britannica, “USB (universal serial bus), technology used to connect computers with peripheral devices such as printers, scanners, and keyboards. A USB port represents a point of connection for USB devices.”
The USB specification was first introduced in the mid 1990s. Since then it has been widely adopted and is now found on nearly all computers and consumer electronics. Early versions of USB, like USB 1.0 and USB 1.1, had maximum data transfer speeds of 12 Mbit/s and 1.5 Mbit/s respectively. Newer iterations like USB 2.0, USB 3.0, USB 3.1, and USB 3.2 offer increasingly faster transfer rates up to 20 Gbit/s for USB 3.2.
One of the key advantages of USB is its “plug-and-play” capability. USB devices can be connected or disconnected without rebooting the computer. The USB host automatically detects and configures USB peripherals when they are attached. This makes it very convenient for users.
USB for Audio
USB ports and connections can definitely be used for audio output and playback. While a standard USB port alone does not carry audio signals, USB can be used to connect audio devices or transfer audio files (1). There are many USB audio devices such as external sound cards, DACs (digital-to-analog converters), amplifiers, and adapters that can enable USB ports to output audio. These devices contain the necessary hardware and software to convert the digital USB data to analog audio signals (2).
USB is actually very well-suited for high quality audio applications because it is a digital interface capable of transmitting the audio data files bit-perfectly. USB audio devices support a wide variety of standard audio formats including MP3, AAC, FLAC, WAV, and more. The USB protocol has the bandwidth to handle high sample rate, high bit-depth audio up to 32-bit/384kHz resolution (3). So USB definitely has the technical capabilities for audiophile quality music playback.
In summary, while USB ports alone don’t carry audio, adding USB audio devices enables USB connections to be used for outputting and playing audio files at very high quality. USB’s digital interface makes it a great choice for music listening applications.
USB Audio Device Classes
The USB Audio Device Class (ADC) enables USB devices to work as audio interfaces for outputting sound. As explained by the USB Implementers Forum, the ADC applies to USB devices or functions that manipulate audio like speakers, headphones, microphones and more. The ADC specification provides standard methods for communication, control and audio data transfer between USB host devices and USB peripheral audio devices.
Per the Keil ADC overview, common uses for ADC devices include playback and recording of audio streams, MIDI musical data, and other related content. The ADC utilizes isochronous USB transfers to enable timely delivery of audio streams. It defines audio formats, sampling rates, bit rates, channel configurations, control requests and more to allow interoperability between diverse audio devices and hosts.
USB DACs
A USB DAC (digital-to-analog converter) is a device that can be used to play high quality audio from a computer or smartphone via USB. The DAC converts the digital audio data into an analog signal that can then be amplified and sent to headphones or speakers.
Using a dedicated external USB DAC rather than the basic built-in audio from a computer’s motherboard or a smartphone can offer substantial improvements in audio quality. This is because USB DACs use higher quality components designed specifically for audio playback.[1]
There are USB DACs available at a wide range of price points from budget models under $100 to audiophile-grade DACs costing over $1000. Higher priced DACs generally offer better components, resulting in lower noise, distortion, and higher maximum resolution. But even basic USB DACs can provide very noticeable improvements over built-in computer or smartphone audio.
USB DACs are powered via the USB connection itself, so no external power supply is required. They can connect to PCs and Macs via USB-A, USB-C, or in some cases USB-micro depending on the model. Many recent smartphones also support connecting to external USB DACs, greatly improving their audio quality potential.
Overall, a USB DAC provides an easy way to tap into the potential of high quality digital audio files by converting the audio and amplifying it optimally for your headphones or speakers.
USB Headphone Amps
USB headphone amplifiers boost the audio signal coming from a computer’s USB port to drive headphones, providing more power and often superior sound quality compared to plugging headphones directly into a computer’s onboard audio. They are small, portable devices that convert your PC or laptop into a high-quality headphone system without the need for an expensive standalone DAC and amplifier (Portable Headphone Amps, 2021).
USB headphone amplifiers have become popular as dedicated external DAC/amps that can drive high-end audiophile headphones which require more power and cleaner signal than a computer’s built-in sound card can provide. Models from companies like Schiit, JDS Labs, Topping and Fiio offer excellent performance in a compact form factor. Many also have a built-in battery so they can be used with mobile devices. Key factors when choosing a USB headphone amplifier are power output, headphone impedance support, signal-to-noise ratio and overall audio transparency (The Best Portable Headphone Amp With Built-In DAC, 2024).
Playing Music Files via USB
One of the most common uses of USB for audio is to play music files stored on a USB flash drive or external hard drive. Popular music file formats like MP3, AAC, FLAC, WMA, and others can be loaded onto a USB drive and then played back through devices with a USB port and audio capabilities.
Many modern car stereos and home audio systems now include a USB port specifically for plugging in a flash drive full of music files. The audio system indexes the music files and allows you to browse and play them back directly from the USB drive. This allows you to bring your full music library with you conveniently in your pocket or bag.
In addition to dedicated stereo systems, you can also play music files from a USB drive using computers, tablets, smartphones, gaming systems, and more. The device just needs to support the necessary audio file formats and have software capable of reading the USB drive and decoding the audio files. The quality of playback will depend on the digital-to-analog converter (DAC) built into the playback device.
USB is popular for playing music files thanks to its simplicity, convenience, and plug-and-play functionality with most devices. You don’t need any special software or wireless connectivity – just copy files onto a USB drive, plug it in, and start listening.
Audio Quality Considerations
The audio quality when playing music via USB can vary depending on several factors:
Bitrate – This refers to the amount of data transmitted per second when playing an audio file. A higher bitrate allows for better audio quality, with CD quality audio having a bitrate of 1411 kbps. Lower bitrates can result in loss of fidelity and detail in the music.
Sample rate – This is measured in kHz and refers to the number of samples or “snapshots” of audio taken per second when digitizing an analog audio signal. A higher sample rate allows for capturing higher frequencies and results in better audio quality. CD quality audio has a sample rate of 44.1 kHz, while high-resolution files can have rates of 96 kHz or higher.
USB version – Newer versions of USB allow for higher data transfer speeds and bandwidth, meaning they can handle high bitrate, high sample rate audio files with no issues. USB 2.0 may have trouble with high-res audio, while USB 3.0, USB 3.1 Gen 1, and USB 3.2 Gen 2 are better equipped for lossless audio playback.(1)
Unsupported Audio Formats
While USB can support playback of popular audio file formats like MP3, WAV, FLAC, AAC, and OGG, there are some proprietary formats that may not work when connecting a USB device directly to a TV or stereo system. Some formats that often face compatibility issues over USB include:
DTS – This surround sound codec format is commonly used on Blu-ray discs and downloadable movie files. Most TVs lack the license to decode DTS audio over USB inputs. Trying to play a DTS file through USB would result in no audio output.
Dolby Digital – Similar to DTS, this surround sound format is popular on DVDs and some digital files. TVs and basic stereo systems likely won’t be able to handle Dolby Digital audio streamed over USB.
AIFF – The Apple Audio Interchange File Format is unsupported on many non-Apple devices. Connecting an AIFF audio file via USB would not produce audio on most TVs or stereos.
WMA Lossless – This uncompressed audio format is owned by Microsoft and primarily used in Windows ecosystems. Due to licensing limitations, most consumer audio products lack WMA Lossless support over USB.
To play these unsupported formats via USB, the audio would need to be converted to a more compatible file type first using a program like FFmpeg. Otherwise, connecting devices that natively support these formats, like Blu-ray players, may be required. Checking the supported formats in a device’s manual can help avoid unusable audio files.
Conclusion
In summary, USB can absolutely be used to play music and audio files. There are several standards and device classes that enable USB audio, including USB Audio Class 1.0, 2.0, and 3.0. These allow USB devices like DACs (digital-to-analog converters), amplifiers, and headphone adapters to output high quality audio when connected to a USB host device. The audio data is transmitted over the USB cable digitally, bypassing the DAC of the host device, resulting in improved audio fidelity. USB audio support is built into operating systems like Windows, Mac OS, Linux, Android, and iOS. The audio quality over USB has continued to improve with each version, with 192kHz/32-bit now possible in USB Audio Class 3.0. While USB may have some limitations compared to other dedicated audio interfaces, it provides an easy and convenient way for many users to play music files stored on their computer through external speakers or headphones.