With the rise of digital technology and music, the DAC (Digital to Analog Converter) has become a central link in any modern hi-fi system. Now integrated into virtually all amplifiers, network players, CD/SACD players, and even smartphones, tablets and computers, it shapes playback, influencing the texture, dynamics and sonic personality of the device. To fully appreciate its importance, we need to look back at its evolution. From the first chips used in CD players in the 80s to today’s sophisticated models, the DAC has undergone profound technological changes. From R-2R converters with discrete resistors to the delta-sigma solutions that dominate today, each generation has brought its share of innovations.
The digital revolution gives rise to the need for conversion
At the beginning of the golden age of hi-fi, from the 1950s to the end of the 1970s, music was based exclusively on analog media: vinyl, magnetic tape or AM/FM radio. The signal flowed seamlessly from the microphone to the speakers, in the form of a continuous electrical wave. Everything changed in 1982 with the arrival of the CD. For the first time, a consumer medium stored music in digital form. This change imposed a new technical constraint: converting a sequence of binary data into an analog signal that could be used by the amplifier.
This is where the DAC arrived. Its fundamental mission was to transform a digital representation of sound (a succession of zeros and ones) into a continuous electrical wave, faithful to the original recording. This analog signal can then be amplified and reproduced by the speakers. The challenge was immense for the time. Circuits had to be fast and precise enough to process streams coded in PCM (Pulse Code Modulation), the format chosen for the 16-bit/44.1kHz Audio CD. The first converters, still rudimentary by today’s standards, were limited by the speed of the components, the stability of the clocks and the precision of the resistor networks. Despite these constraints, they paved the way for a major technological revolution.
Note from the expert The sampling frequency, expressed in kilohertz (kHz), is the number of times per second the analog signal is "measured": 44.1kHz means 44,100 samples per second, 96kHz is 96,000. The higher this value, the more accurate the theoretical reproduction of high frequencies. Bit depth, on the other hand, defines the dynamic resolution of each sample. A 16-bit coding allows some 65,000 possible amplitude steps, while 24 bits offer over 16 million, considerably increasing the dynamic range and finesse of micro-details.
The first DACs for CD players
In the ’80s, the advent of CD players did not go down well with audiophiles, who criticized CDs for their lack of warmth and realism compared to vinyl records. The fault lay mainly with the players’ unsophisticated internal DACs, which made a myriad of errors in digital signal processing. The playback mechanism transmitted digital data irregularly, causing decoding errors. This phenomenon, known as jitter, is responsible for overlapping musical information in the high frequencies, resulting in a narrow soundstage and a certain harshness.
At the same time, alongside the solutions offered by consumer manufacturers, initiatives were being launched to improve digital-to-analog conversion. Devices such as the 1987 Covox Speech Thing, although intended for simple computer applications, showed that it was possible to extract a usable analog signal from a digital stream at a lower cost. In practice, these devices used very basic architectures based on resistor networks to convert a digital signal into an analog voltage. Their ambition remained modest, but they already revealed that conversion is not a mere technical detail: it has a direct influence on perceived quality.
During the same period, another phenomenon appeared with the first mass-market CD players. Although they offered a reproduction that was technically correct, certain flaws associated with digital processing became audible. Correcting these errors meant integrating additional processors into the players, with specific software development and considerable additional costs. For most manufacturers, the economic equation didn’t justify a complete circuit redesign. With the exception of a few high-end models, in-depth conversion optimization therefore remained marginal.
This paved the way for a niche market: that of external converters. Rather than replace their CD player entirely, music lovers began to use its digital output and entrust conversion to a dedicated device: the audio DAC. This movement, which gained momentum in the 1990s, marked a decisive turning point: the DAC ceased to be a simple integrated component and became a fully-fledged link in the hi-fi chain.
Some brands, however, adopted an ambitious approach early on. At Marantz, for example, the source has always been considered the true starting point for music reproduction. As early as 1982, when the CD was in its infancy, the brand, then associated with Philips, entrusted Ken Ishiwata with the optimization of the Philips CD100 player. The result was the Marantz CD-45, with its revamped power supply and improved conversion stage.
More than four decades later, the fundamental principle of the DAC remains unchanged, but it has profoundly evolved in terms of accessibility, integration and performance. External DACs have become particularly affordable and versatile. They provide audio conversion from a computer, smartphone or tablet via USB, while also supporting S/PDIF sources such as a network player, CD player or TV. At the same time, the miniaturization and increased performance of electronic components have enabled conversion circuits to be standardized. High-quality chips, once reserved for high-end devices, are now integrated into numerous amplifiers, CD players and streamers.
R-2R and Delta-Sigma: two conversion philosophies
As DACs have evolved, two major innovations have come to the fore: R-2R resistor-array converters and delta-sigma DACs. The R-2R DAC is one of the very first conversion architectures adopted in CD players. It relies on a precise resistor network to convert a digital signal into an analog voltage. Each bit of the binary signal corresponds to a voltage step calculated by the network, giving a very direct approach to the analog signal. Fidelity is highly dependent on the precision of the resistors and the stability of the switches, but when well designed, this type of DAC offers a smooth, natural musical reproduction, often described as more analog-sounding.
Long relegated to the background due to its high production costs and complexity of implementation, the R-2R DAC is now enjoying a genuine revival. Advances in precision component manufacturing and automated resistor sorting now make it possible to optimize linearity while keeping costs under control. Manufacturers such as FiiO are playing an active part in this rediscovery by integrating R-2R architectures into USB DACs, CD players and DAPs, helping to make this technology, previously reserved for very high-end devices, more accessible.
In contrast, delta-sigma DACs are based on a different principle. Rather than directly creating an analog voltage proportional to the digital value, they use an electronic chip with a modulation and filtering technique. The digital signal is first transformed into a very high-frequency bitstream (often much higher than the final sampling frequency), then digital filtering reduces the quantization noise to reconstruct the audio signal. This approach makes it possible to achieve high performance with components that require less tolerance, which is why it has become dominant in the industry.
From external DACs to integrated chips
From the 2000s onwards, the DAC underwent a major transformation, signaling the decline of the often very expensive high-end external DACs. Advances in semiconductor technology and the miniaturization of integrated circuits enabled DACs to be integrated into a multitude of products: smartphones, tablets, network players, TVs, Blu-ray players and even active speakers. Chip manufacturers such as ESS Technology, AKM and Texas Instruments dominate this market, offering high-quality integrated delta-sigma DACs that are becoming the basis of many consumer and audiophile audio solutions. This large-scale integration drives down costs while improving the overall performance of digital audio systems.
Today, high-quality audio conversion is accessible to the widest possible audience. Whereas a high-end external DAC might have been an investment reserved for audiophiles, the presence of high-performance DACs in consumer devices such as all-in-one amplifiers or network players means that a wider range of listeners can benefit from clean conversion without major additional costs.
However, the external DAC is still relevant today. While converters integrated into connected amplifiers, network players and other all-in-one solutions have made considerable progress, those embedded in laptops and smartphones are still subject to the constraints inherent to compactness, low power consumption and low cost, which limits their performance. To get the most out of Hi-Res files, whether they’re high-definition PCM or DSD, a dedicated external DAC generally offers a more accurate power supply, a more stable clock and better-sized analog stages. It can also be a useful upgrade for a system equipped with an older-generation CD player. As conversion precision, jitter management and performance have greatly evolved over the years, entrusting the digital signal from a CD transport to a modern DAC often makes it possible to restore legibility, finesse and depth to an otherwise familiar disc collection.
From the rudimentary converters found in CD players, through the R-2R and delta-sigma architectures that have shaped their performance, to the sophisticated chips built into almost all modern devices, DAC developments have always been at the heart of more faithful sound reproduction. Today, the role of the DAC is twofold: it is both an essential bridge between the digital and analog worlds and a constant field of innovation, where engineers compete to achieve the purest, most natural and most musical reproduction possible.
