How to Choose a DAC
A DAC (Digital to Analog Converter) is a device that converts digital audio input signals to an analog output. It turns all those pesky 1s and 0s into music! There is a DAC inside every digital music device with analog (RCA, XLR, speaker, or headphone) outputs.
If many smartphones, computers, and CD players already have a DAC, why would you need to choose another?
The basic DAC included in most consumer devices is always a trade-off between quality and cost. Sure, the included DAC may convert the signal, but a discrete external DAC will simply sound better. At the heart of a DAC is the digital processing circuitry that performs the conversion from the digital to the analog realm. No two DACs do it the same, and different implementations sound unique from each other.
Since a DAC is a computing device, and technology marches inevitably along, DAC size keeps decreasing while processing power increases. In general, today’s DACs sound better than those from years past, and the sound quality from modern, relatively inexpensive devices can be astonishingly good.
While most folks will be satisfied by the sound quality of an included DAC, audio enthusiasts and audiophiles will always be searching for better. Whether to improve audio quality, resolve issues, or decode a greater range of file types, it is crucial to choose the right DAC for your needs. A new DAC should offer better sound and support new features (such as high-resolution audio, DSD, or MQA decoding).
Desktop or Portable DACs
In choosing a DAC, the first step is to decide where you want to use it. Do you want a DAC that is portable and that you can use on the go? Or is your DAC going to be only for stationary desktop usage?
A desktop DAC is typically larger and heavier than a portable model. The desktop model likely features multiple digital inputs and possibly several analog outputs. It plugs into the wall outlet for power, lacks an internal battery, and may include a remote control.
Portable DACs are designed for mobility and to be connected to phones, tablets, and digital transports. Portable DACs may be shaped like small dongles and use the source device for power (such as the iBasso DC04 or HiBy FC3) or may be somewhat larger (starting at about the side of a deck of cards) and contain an internal battery (such as the AUNE BU1 or xDuoo XD-05 series). Often folks tether their phone to an external portable DAC with specialized rubber bands designed for this purpose.
Portable DACs are almost always combination devices that include both a DAC decoder and an internal amplifier to drive headphones (an integrated DAC/amp device). As a basic rule of thumb, the larger the portable device, the more output power it has (although you must check the specifications for details). Some even include more powerful, balanced headphone outputs (such as the Fiio Q1 Mark II).
Desktop DACs may be combination DAC/amp devices (such as the DAART Yulong Aquila II) or solely a dedicated DAC unable to drive headphones directly (such as the SMSL SU-9). Integrated DAC/amp desktop devices are typically simpler to use. They may be less expensive than separate components, cleaner looking, require less desk space, and designed to sound the best paired with their internal amplifier. Most of these devices have analog outputs, so they allow for connection to more than one amplifier.
Of course, a portable DAC may be used on your desktop (while the opposite isn’t true). However, portable DACs often compromise features or output power to maintain their small size. For the same price, an integrated desktop DAC/amp will typically offer a better ability to drive a broader range of headphones and include a greater number of inputs and outputs.
The Specs Matter
While reading a DAC’s bulleted list of specifications may make your eyes glaze over, it’s here that helps you the most with differentiating between DACs and choosing one over another. Modern DACs are incredibly powerful and complicated. They support a vast amount of digital file formats and are the most complex part of the audio chain. Comparing the specifications is a crucial part of the decision process.
You need to figure out what features are required. If you are shopping for a portable DAC, the size, weight, and internal battery are vital considerations. Beyond that, the essential aspects are shared between desktop and mobile options. You must ask yourself what is important to you.
If you want an integrated DAC/Amp, you must consider the output power and headphones you want to drive. If you are only looking to power super-efficient IEMs, a lower-powered and quieter amplifier may be preferred. If you’ve got inefficient full-sized monster headphones, a high-voltage or high-current capable amplifier is required.
Are you looking to connect your DAC to external components? Are various digital inputs (S/PDIF optical or coaxial as well as USB) important to you? Do you require balanced XLR outputs, or is RCA sufficient? Do you want the ability to function as a preamp and control the volume for powered speakers? How about Bluetooth support?
What digital file formats are supported? Newer high-resolution audio formats (DSD and MQA) have increased in popularity over the last few years. While 16-bit/44kHz standard CD audio format still sounds great, how important is it to you if your DAC supports 24 or 32-bit decoding? Is it crucial if it supports sample rates up to 768kHz? Even if you don’t currently listen to those formats, it never hurts to have a DAC that boasts the widest format compatibility for the sake of future proofing.
But wait! Aren’t we forgetting something important? How about sound quality?
The internal architecture of a DAC has the most significant influence on its ultimate sound quality. DACs are inherently imperfect. For better or worse, they can only approximate an analog signal, and whatever method they use to do so has inherent inaccuracy. DACs are never flawless, although this may or may not be audible.
DACs either use a converter chip (Delta-Sigma or FPGA) or a series of resistors (R2R) to perform the conversion. Filtering is applied to smooth the steps between the digital audio samples and to approximate a smooth analog waveform. These filters are a form of a mathematical algorithm and typically predict values based on values before and after each discrete sample. Some DACs pick the best filter for you, while others allow you to choose between multiple filter options.
The implementation of the components within the DAC also has an impact on the sound. Even if two devices share the same DAC chip (and many do), they will not necessarily sound identical. The choice of power supply and output stage also plays a role.
All this being said, most DACs these days sound remarkably good. Differences tend to be pretty subtle, especially between DACs sharing the same chip or family of chips. AKM, ESS Sabre, and Texas Instrument Burr-Brown chipsets are the common architectures you will encounter. The only way to know for sure what you like the best is to try listening to them yourself.
Author Trav Wilson: Audiophile or Audio-Phool? I don’t claim to have golden ears with magical properties, nor any ability to create music. But I do have a deep appreciation for music, founded at a young age, and curated over the years. I’m also unapologetically a gear-head and love lights, buttons, meters, switches, and especially things made from traditional wood, leather, metal, and glass materials. As with everything, take it for what it is: this is just one person’s opinion. Runs noteworthy.audio