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Why A High-End Music Server Is Necessary

This article delves into why a multi-stage, high-end music server is necessary in order to get a high-end audio experience from streaming services and playing music files.

Digital audio binary data, represented by ones and zeros, records the amplitude of sound samples. However, the integrity of the digital signal is not solely dependent on the accuracy of these amplitudes. Timing plays an equally vital role and the timing of the signal is created by the music server used. Imagine a turntable with high frequency wow and flutter distorting the signal's timing and you begin to realise that the ones and zeros are only half of the picture.

In digital audio, unlike its analogue counterpart, timing inaccuracies can be reduced during playback. This is achieved through buffering and regenerating the digital signal, and synchronising it with a low phase noise clock, in a circuit that is well designed to maintain its stability. This process enhances the quality of the digital signal in the time dimension, and therefore it enhances the sound quality of the resulting analogue audio.

This characteristic of digital audio leads to a common misconception that as long as one possesses a high-quality DAC, with a high precision clock, then the quality of the music server is inconsequential. The rationale behind this misconception is that this DAC will be able to perfectly time the data just before the digital-to-analogue conversion.

Of course, there are individuals that are absolutely vehement that it is all just ones and zeroes, so a music server-streamer cannot make a difference. This is so easily dis-proven by listening that it is hard to understand how this fallacy persists. The writings of Neuroscientist Iain McGilchrist on left and right brain thinking give us a clue: “the left hemisphere sees truth as internal coherence of the system, not correspondence with the reality we experience.”; “Meaning emerges from engagement with the world, not from abstract contemplation of it.”; “The only certainty, it seems to me, is that those who believe they are certainly right are certainly wrong.”

Just because perfect digital is theoretically possible, does not mean that real-world circuits can so easily achieve a perfect, or even a good result. In practice, good results require excellent circuit design and multiple stages, amongst other real-world factors. In practice, achieving precise signal timing before the DAC always improves the resulting analogue audio quality.

We have previously used the analogy of cleaning a very dirty car. While it is theoretically possible that a single step might do a good job of cleaning the car, a multi-stage process of pressure cleaning, wiping-down with soap and water, rinsing, waxing and polishing, yields a far superior result in practice.

As an example, a clock stage is only as good as the circuit it is used in and the power supply that powers the circuit. And the re-clocking stage needs to receive a low-noise signal with high-bandwidth, before it can re-clock the signal accurately. If the signals before and after the re-clocking stage are polluted by noise below the bit-rate (such as from employing linear power supplies) then the re-clocking will be largely ineffective. Anyone that claims that digital is 'just ones and zeroes' has not applied their knowledge to demanding real-world problems.

The necessity for high-end audio equipment to perform the music server stage stems from at least three factors:

1. Noise Reduction: Music servers can be engineered with sufficient power, specialised power supplies and circuit designs that isolate the digital signal from electrical noise. Noise, prevalent in general-purpose computers and networks, can significantly degrade audio quality.
2. Isolation: Isolating processor-intensive digital signal processing from analogue signals is crucial. What will yield the best digital signal will interfere with analogue signals and vice versa.
3. Dedicated Audio Optimisation: High-end music servers can be optimised for audio playback. This includes the use of high-quality components, optimised operating systems and software applications, and optimised management of services to avoid time-based distortion of the signal.

DACs play a pivotal role in digital audio playback, and so too do Music Servers. It is the quality of both the Music Server and the DAC that delivers the quality of the resulting analogue audio signal.

Choosing A Music Server

Objectivity Versus Relevance

Audiophiles face something of a challenge, to select separate pieces of equipment that will combine to form a system that deeply resonates on an emotional level.

The most objective approach to evaluating audio equipment is through its technical specifications. While these specs provide a quantitative measure of performance, they fall a long way short in predicting the emotional impact of the music played. An alternative method involves listening to the equipment to discern fine detail retrieval, accuracy of timbres, and dynamic immediacy, etc. Though subjective, this approach offers better insights into an equipment’s potential to fulfill music's emotional purpose, than merely reading the specifications.

The third and most relevant method is to listen and gauge your emotional connection with the music. Despite its subjective nature and variability, this approach aligns directly with music's sole objective - your emotional reaction to it. The more relevant evaluation methods are more subjective.

Practicalities

Assembling a high-end audio system is a delicate balancing act, especially concerning overall tonal balance and accuracy of timbre of instruments and voices. For example, audiophiles often find themselves balancing the yin and yang of different components to arrive at an exciting, yet natural and organic sound. It is important to do this well because unnatural sound will get in the way of emotional connection. But this is not the same as evaluating emotional connection.

The focus on fine-tuning sound characteristics can lead to a well-balanced system that, paradoxically, lacks emotional engagement. Emotional engagement, the very essence of music, can be lost in the pursuit of sonic perfection. Most audiophiles have experienced this at some point, finding that they are no longer listening to their music as often, and yet the sound is hard to fault. Some find themselves flicking through tracks to hear ‘exciting’ moments in tracks, rather than enjoying the piece of music itself.

Music Servers

This problem is particularly pronounced in the selection of music servers. Historically, music servers have struggled to convey the emotional content in music, despite their proficiency in resolving fine details and dynamics while maintaining tonal balance. Therefore, when selecting a music server, it becomes even more important to prioritize emotional evaluation over cognitive analysis.

Music servers are a gateway to vast digital music libraries and their ability, or inability, to deliver music with emotional depth should be important to every audiophile that wishes to continue exploring music. It is relatively simple to make a music server that will deliver detail and bombast. And so it is relatively easy to make a music server that delivers ‘impressive’ sound. What really distinguishes a great music server is its ability to stop you listening to the sound, and allow you to feel the emotions evoked by the music, and so we strongly recommend that you focus your evaluation of music servers on the way the music makes you feel.

The Best Connection To Your DAC

Introduction

This article delves into what to consider when deciding on the connection between your music server and your DAC.

A Question Of Architecture

The concept of 'architecture' in this context refers to the distribution of processing tasks between the music server and the DAC. Understanding this is essential for making a well-informed decision.

Different music servers may do things a bit differently, but the point can be illustrated by considering a computer audio solution that consists of four key stages:

1. Server App: Initiates the process by streaming data to the player app via Ethernet.
2. Player App: Regenerates and transmits the data to a regeneration step via USB.
3. Signal Regeneration: Buffers the signal and generates a new low-noise high-bandwidth signal representing the same sample amplitude data.
4. Signal Clocking: Re-clocks the signal with reference to a stable, low-phase-error, precise clock.

The implications of using different connections:

1. Ethernet: Using Ethernet means the music server only performs the Server App step and the DAC performs the rest.
2. USB: Using USB means the Server App, Player App and regeneration step are performed in the music server and precise-clocking is left entirely to the DAC.
3. S/PDIF, AES3 or I2S: Using S/PDIF, AES3 or I2S means the Server and Player Apps, regeneration and re-clocking are performed in the music server, and the DAC's re-clocking is applied to a cleaner signal. However, remember that S/PDIF and AES3 have only low bandwidth transmission capabilities.

Some Generalisations

Your decision hinges mainly on the relative quality of your music server and DAC:

1. If Your DAC Is Superior: Choose the Ethernet connection, which shifts the job of fixing the signal entirely to your DAC. This is less than ideal but makes sense when using a basic computer or a low quality music server with a good DAC.
2. If Your Music Server Is Superior: Choose a connection like S/PDIF, AES3, or I2S, leveraging the server's higher quality for more of the processing steps.
3. If Both Are Of Similar Quality: This is the ideal solution and you can choose USB, S/PDIF, AES3, or I2S, to lighten the processing load on the DAC.

A Possible Exception: Multi-Box DACs

In a typical two-box DAC, digital signal processing steps occur in the first box, to deliver a precisely clocked signal sent to the second box for the DAC step. This design is consistent with the point made earlier about keeping demanding computational steps separated from the digital to analogue conversion. Our experience at Antipodes suggests that using regeneration and reclocking in our Oladra music server typically yields superior results. But you should experiment for yourself.

Conclusion

Choosing the right connection between your music server and DAC is not about finding the best interface but deciding where each processing step should ideally occur. The decision needs to be based on the individual strengths of your music server and DAC, with a bias towards lightening the processing load on your DAC.