Can Android play audio through USB?
Playing audio over USB has become a common feature on smartphones, allowing users to connect to external DACs (digital-to-analog converters), amplifiers, and other audio equipment. However, Android’s support for USB audio has been inconsistent across different versions and phone models.
The Android operating system is developed by Google as open source, but phone manufacturers like Samsung can modify the OS for their specific devices. As a result, USB audio support relies both on the core Android OS version as well as hardware drivers from the phone maker. Older Android versions lacked native USB audio capabilities, forcing users to find workarounds. Partial USB audio support was later added, but it remained limited and fractured due to reliance on proprietary drivers.
Android’s Initial Lack of USB Audio Support
Early Android devices like those from Samsung, HTC, and others lacked any built-in USB audio support. This meant that users could not connect their phones directly to external USB DACs, amplifiers or USB speakers. The only audio output options were the headphone jack or Bluetooth wireless audio (1).
There were some exceptions, like specialized docks made for particular phones that had custom drivers to enable USB audio. But in general, Android did not support the USB Audio Class standard that allowed audio to be transported over a USB connection (2).
This limitation was frustrating for audiophiles who wanted to take advantage of high quality external USB DACs. It also made it difficult to connect Android devices to USB speakers or audio systems. The only option was to use wireless Bluetooth streaming which had bandwidth limitations and compression. Early Android was simply not designed with digital USB audio output in mind (3).
Partial USB Audio Support Added
Android’s initial lack of USB audio support began to change in 2011 with the release of Android 3.1 Honeycomb. This version added partial support for USB audio devices like headphones, speakers, and microphones (Source: https://source.android.com/docs/core/audio/usb).
However, Android 3.1’s USB audio implementation was still incomplete. It required device manufacturers to provide custom drivers to enable USB audio support, and even then, compatibility was spotty with many USB audio devices simply not working. There were also reports of USB audio randomly stopping during use on some devices running Android 3.1 (Source: https://www.quora.com/How-do-I-enable-USB-audio-on-Android).
So while Android 3.1 was a step forward, USB audio support on Android remained fragmented and unreliable at this stage.
USB Audio Class Standard
The USB Audio Class standard was created to simplify USB audio support across devices. As explained on the EDN article “Fundamentals of USB Audio,” the USB Audio Class specification provides a common standard for USB audio devices to ensure broad compatibility. It covers a wide range of audio devices including complex mixing desks, multi-channel interfaces, and simple headsets. The specification provides details on aspects like audio formats, sampling rates, clock sources, and more.
Prior to the standard, USB audio implementations were fragmented and required custom drivers on the host side. This led to compatibility issues. As noted in a discussion on Audiokarma “USB 1.1 vs 2.0 (audio class) Discussion,” the USB Audio Class standard helped address these problems by establishing a common way for USB audio devices to identify themselves and be recognized by hosts. This allowed generic USB audio drivers to be used, improving plug-and-play functionality across devices.
USB Audio Class Adoption
In 2014, Android 5.0 (API level 21) fully supported the USB Audio Class 1 standard (source). This allowed plug-and-play audio output over USB, so that Android devices could connect to external USB DACs and amplifiers. The USB Audio Class 1 implementation in Android 5.0 enabled high-quality digital audio output through the USB port without the need for proprietary accessory modes or custom drivers.
However, some Android OEMs were slow to adopt support for the USB Audio Class standard in their devices (source). So while Android supported USB audio as of 5.0, many Android phones and tablets still lacked proper USB DAC functionality due to lack of OEM support. This caused frustration for Android users wanting to use external USB audio devices. The situation has improved over time as more OEMs enabled USB Audio Class support.
USB-C Improved Compatibility
The introduction of USB-C ports on smartphones improved compatibility for audio output over USB. Unlike the older micro-USB ports, USB-C ports could transmit audio digitally, enabling higher quality audio compared to analog 3.5mm connections (www.androidauthority.com). This digitization made audio transmission more consistent across devices with USB-C. No longer was an analog conversion required which could result in quality fluctuations.
By switching to USB-C, manufacturers could guarantee the digital-to-analog conversion was done properly in one place – the USB-C headphone adapter. Rather than relying on the internal smartphone DAC, the conversion was offloaded. USB-C ensured the signal remained digital until the last step, maximizing quality (www.reddit.com/r/headphones).
Bluetooth as an Alternative
While USB audio support was limited in earlier versions of Android, Bluetooth offered an alternative for wireless audio streaming. Bluetooth technology has been included in Android devices since the beginning, allowing users to pair headphones, speakers, and other audio devices wirelessly.
However, Bluetooth audio quality can vary greatly depending on the Bluetooth version used. Older versions like Bluetooth 2.0 have limited bandwidth, resulting in lower audio quality typically capped at 96 kbps (according to mp4gain.com). Newer versions like Bluetooth 5.0 support higher bitrates up to 512 kbps, but audio quality still depends on the headphones/speakers and source content.
Bluetooth streaming also suffers from latency and reliability issues in some cases. The encoding and wireless transmission introduces lag between the audio source and output. Interference can cause stuttering and dropouts. While Bluetooth provides wireless flexibility, audio fidelity and timing accuracy is reduced compared to wired connections.
USB DACs for Audiophiles
External USB DACs (digital-to-analog converters) can provide higher quality audio than relying on a phone’s built-in DAC. As explained by redditors on r/audiophile, “An external DAC is great if your computer introduces a lot of EMI. I used to have a work computer where you could hear the mouse scrolling in the background” (source). By bypassing the internal DAC and using a dedicated external DAC, interference can be reduced resulting in cleaner analog audio output.
However, in order to use an external USB DAC, the device must support the USB Audio Class standard. As SoundGuys explains, “If the USB DAC includes a headphone amplifier with a decent power output, then yes, it will help drive your headphones properly to get the most out of them” (source). So while USB DACs can provide audiophile-level sound quality, USB Audio Class support is needed to take advantage of external DACs.
USB Audio Support Today
Modern Android versions like Android 12 and newer have full support for USB audio, enabled by default. This allows audio output over USB-C to external DACs and amplifiers. However, Android’s fragmentation means experiences can still vary across devices. For example, some manufacturers disable USB audio in their Android skins like MIUI, ColorOS or FunTouchOS, requiring users to enable it manually.
Accessory compatibility also remains a factor. Not all USB-C to 3.5mm adapters properly support USB audio, so users need to choose adapters that specifically mention USB audio support. High quality USB DACs generally work reliably, but cheaper USB-C to 3.5mm adapters can be hit-or-miss depending on the chipset used.
Overall, while USB audio support is now quite robust in Android, factors like older devices, manufacturer customizations and accessory compatibility mean the experience is not always seamless. Careful accessory selection and software tweaking may still be needed in some cases.
Conclusion
In summary, Android has had a winding journey in terms of USB audio support. The operating system did not originally support USB audio out of the box. Over time, partial support was added through various partnerships and initiatives. The standard USB Audio Class was eventually more widely adopted by Android and hardware makers. The emergence of USB-C has improved compatibility for many phones. However, direct USB audio out remains imperfect even today on some devices.
The good news is that most Android phones and tablets released within the last few years do support basic USB audio out functionality. Users can connect to amplifiers, USB speakers, and more. However, factors like the exact SoC, USB controller, and audio codec used in the device impact quality and reliability. For discerning listeners and audiophiles, standalone USB DACs can provide improved fidelity. But average users should find their Android device provides sufficient USB audio capabilities for most use cases today.
