Select and integrate audiophile-quality components

 Digital audio technology has opened the door to many possibilities as we await the next digital evolution
which is music streaming.

Technology that is fast evolving

Today’s digital audio has come a long way since the invention of the Compact Disc. The high-end audio industry has split the CD player into 2 parts; transport only and a standalone outboard DAC (Digital to Analogue Convertor). They also made jitter devices and special digital cables that promise high speed and higher bandwidth transmission. The outboard DAC would also serve other audio applications and facilitate further improvement possibilities as a standalone purpose-built component. DACs in general has been improved with new generation chips, clocks, and interfaces finding their way into active loudspeakers, soundbars, desktop computers, gaming consoles, DAC amplifiers for headphones, and creative dongles for use with mobile phones and tablets. This paves the way for higher bit rates and sampling formats catering to the audiophile community. Today, we welcome music streaming which, I believe in a matter of time will inevitably deliver the killer blow to the Compact Disc.

A Transport Player (see illustration) has no DAC built-in unlike a CD (compact disc) player but only extracts the data from a compact disc and spits out the bits through its output connectors. A Transport Player has a motor mechanism to spin the CD and capture the bits through its laser mechanism. It also incorporates a power supply section.

Player

A CD player (see illustration) is a Transport Player with a DAC integrated into the housing spitting out analog signals through its output connectors usually single-ended RCAs but may have XLR balanced on some models. Certain models may incorporate digital output connectors which allow the CD player to act as a Transport Player bypassing the stock DAC as an option for a preferred outboard DAC.

Streamer

The Streamer is a computing device used to stream music from the cloud via a streaming service provider for playback or to download music into their built-in storage system if available. The Streamer (see illustration) would be linked to the internet by its inputs from a router or by WiFi (wireless) through a modem. It may incorporate a DAC (where it will be known as a Network Player) and or may be used as a Transport player if there is a digital output or may incorporate features to rip music from a CD into a storage device incorporated in the housing. Music could also be sent from an external storage device via a home server for music playback or through Bluetooth connectivity. The Streamer may also incorporate a preamplifier feature that routes the analog signal straight to a power amplifier of choice. The Streamer may be a convenient total solution in a box, however, the more features it has, the more it will cost, moreover, you will lose the ability to try better DACs unless it also has a digital output option.

1. A Delta-Sigma Modulator utilizes the manufacturer's preferred chip e.g., AKM, Burr Brown, Cirrus Logic, ESS Sabre, Texas Instruments, etc. which have fixed parameters. The Delta Sigma model is fast evolving with better chips improving sound quality. They boast superior dynamics at both the extreme highs and lows.

 Just be mindful when using coax for a preferred outboard DAC, some DACs coax inputs don’t support DSD or MQA unless you use the USB (Universal Serial Bus) interface connect if available. USB-B or C is an industry-standard connector for transmitting both data and power on a single cable. USB-B connector 2.0 has a top speed of 480 Mbps while USB-B connector 3.0 has a top speed of 5Gbps. The USB-C connector has a reverse plug functionality and is physically similar to the existing Micro-B USB variant. Type-C supports USB connector 3.1 and offers a top speed of 10 Gbps for data transmission. It also has a significantly higher power output of up to 20 Volts 100 W and 5 amps. The optical (Toslink - Toshiba Link) connection uses light to transmit data through a cable’s optical fibers and is known to suffer from jitter. Toslink is usually restricted to 96kHz so they may find their use in soundbars or AV receivers to transmit compressed Dolby Digital and DTS surround sound.

Sound Quality

 Some quarters would argue that a particular chip would contribute to good sound quality. I believe a renowned chip may contribute in part but cannot guarantee the better sound quality, it requires the entire circuitry instead of the sum of its parts. Two manufacturers may use the same chip but both components will sound different in an A/B test comparison. Perhaps an important factor would be a well-executed Power supply. The power supply for example is important for noise isolation, providing stable multi-regulation that serves each relevant section on the board, or a Class A linear power regenerator with supercapacitors to supply extra current when needed will surely make a difference in sound quality. The Printed Circuit Board should have discrete electronics and a clever layout that separates both channels (dual mono) from crosstalk and other interference (distortion). The signal-to-noise ratio in this respect should be as low as possible either interference from RF or EMI or electrical noise from the circuitry. Cables should be well-shielded, with Balanced signal topology, if possible, for RF and EMI rejection. For electrical noise, the use of an isolation transformer (Galvanic isolation) or optical isolation converting the digital outputs signal into ‘light’ are practical solutions to these problems.

 The digital interface input circuitry in the transport system should be well executed to control jitter. This is comprised of an I squared S (I2S) format where three (master clock, word clock, and serial data) separate lines carry the respective information, however, the SPDIF output connections carry all the information in one package. Therefore, Jitter is a product where the timing of the information is not in absolute sync because of the clock quality. A precision Clock Oscillator is essential to drive the DAC chip and the crystal location should be as close to the DAC chip to minimize timing errors so that the signal can be fully reconstructed. Moreover, a quality player should have a bit-perfect transfer for lossless files to receive and send data. Therefore, the use of USB connections with music encoded with either FLAC or Apple ALAC codecs is necessary.

 I believe a critical contributor to sound quality is the analog output section that converts the current from the chip to a voltage to drive the amplifier, and every manufacturer has a different way of implementing this. Therefore, when people say that bits are bits and that ones and zeros cannot make the sound different, in my experience they are not schooled in critical listening and hence are not audiophiles. Their opinions should be disregarded no matter what their engineering credentials or audio affiliations are.

Streaming Services

 The choice for streaming services should be evaluated based on their subscription rates on a given package, user experience (ease of use and search), a library of content (comprehensiveness of music you like), and most important of all - sound quality (should at least be CD quality). However, sound quality is dependent on the file formats available for streaming or download by the streaming providers. The mastering engineer will prepare several versions from the same reference master to suit the music servers’ specifications, radio, and other music providers. They will tailor the files for each media company; therefore, they may sound different even from the same file format and you won’t know which distribution copy is being used. That means you may hear a difference between the same music file from Streaming Service A and Streaming Service B when you conduct an A/B test comparison with all things being equal. Nevertheless, streaming offers not only ease of music consumption but it provides an opportunity for exploring new music or recommendations made from other sources. There is also an option to purchase the song online to download and archive them. However, you need to subscribe to a service provider and pay a yearly recurring subscription fee to continue with the service. Moreover, you may not get the song that you want because of the limited availability notwithstanding the desired specifications for high-res files. 

 The following are some of the popular streaming services that you may want to consider, as in all technology and business dynamics, the information may be outdated at the time of this writing:

Tidal - offers audio quality streaming on iOS, Android, desktop app, web player on FLAC or AAC files, or MQA on Tidal Masters (typically 24-bit/96kHz) hi-res streaming. Tidal has 2 types of plans (1) Premium plan with standard (320kbps) sound quality and (2) HiFi plan with lossless audio (CD-quality streaming, 24-bit/96kHz) albeit with a higher monthly subscription.

Qobuz - offers to stream and download high-resolution audio in true CD quality and 24-bit high-resolution on iOS, Android, desktop apps, and web players on FLAC files. They have 3 types of plans (1) GBP plan with 320kbps quality, (2) ‘Hi-Fi’ plan with 16-bit/44.1kHz music, and (3) ‘Sublime’ plan with 24-bit/192kHz high-resolution audio.

Amazon HD - offers its CD-quality and high-res music streaming service. Accessible through a dedicated desktop app or a mobile app (available for Android and iOS devices, desktop app, web player). Amazon HD, label tracks HD which means CD-quality (16-bit/44.1kHz). Tracks labeled Ultra HD, (Ultra High Definition) are hi-res music (24-bit/192kHz).

Apple Music lossless - Apple has developed its lossless audio compression technology called Apple Lossless Audio Codec (ALAC). In addition to AAC, the entire Apple Music catalog is now also encoded using ALAC in resolution format ranging from 16-bit/44.1 kHz (CD Quality) up to 24-bit/192 kHz. Apple Music subscribers will also be able to listen to more than 75 million songs in Lossless Audio at no additional cost.

Deezer Elite – Deezer offers millions of songs on-demand like its Premium+ plan, it also provides music in CD quality; Deezer HiFi level 16-bit, 44.1kHz stored as FLAC, WAV, or other types of lossless file formats at 1411 kbps for quality audio.

Spotify: It is rumored that Spotify may offer to stream in CD quality.

Music interface and audio player applications

Music interfaces/audio players are necessary when streaming music. The following are some of the popular audio players that may be used with the various streaming services:

Roon - which can be installed on your Mac or PC, Linux, or Intel NUC. Roon Remote – this will let you browse your library from your iPad or iPhone, using the same rich interface as the desktop. Roon Focus – this feature goes beyond your library, giving you a 360º-view of artists, genres, performers, and composers.

JRiver Media Center - supports all lossless formats for audio (FLAC, APE, ALAC, WMA lossless, Apple Lossless, and WavPack) AIFF and WAV files. DSD support (ASIO v2.2, DoP, SACD, DFF, DSF, etc.). JRiver also supports WASAPI to communicate with a DAC on Windows. Can assist to rip CDs in your drive.

Volumio Audio Player - provides bit-perfect audio quality. It can access and be controlled with Mac, PC, Android, iOS, or anything with a browser. Can be installed on the Raspberry Pi and many other silent micro-Computers, as well as PCs and Notebooks.

Moode Audio Player - their latest version claims to have a responsive Adaptive User Interface, an extensive set of Audiophile options, and support for a wide variety of audio devices designed to work with the Raspberry Pi family of Single Board Computers. 64-bit driver support for Allo USBridge and RoonBridge, Qobuz, and Tidal access via UPnP.

Hi-res music streaming file formats and downloads

Hi-res audio refers to music files that have a higher sampling frequency and/or bit depth greater than CD – which is standard Red Book specified at 16-bit/44.1kHz. Hi-res files are generally FLAC files (uncompressed) 24-bit/48kHz, a higher resolution format would be 24-bit/96kHz or an ultra-high-resolution format would be 24-bit/192kHz. Music streaming services stream music in MP3 file formats between 60 to 320 Kbps and for some lossless PCM formats (CD quality) at 1142 Kbps.

DXD – means Digital Extreme Definition. This is a 24-bit or 32-bit PCM with a higher sampling rate of 352.8KHz. DXD is a format for post-processing (to edit) DSD-originated digital recordings. It was also endorsed by both Sony and Phillips as a viable tool for the preparation of SACD masters. DXD was initially developed by Merging Technologies for their Pyramix DSD workstation. Most DSD acoustic recordings offer multi-track recording/editing and mixing as well as mastering into a DXD edited master and converting through the Pyramix digital mixer back to DSD and up to the final SACD master. There are a few modern DACs that support the DXD format and even a few digital music stores that convert the original DXD files available for download in a variety of formats including 192 kHz/24-bit FLAC as the PCM container and DSD 64 files. Some DXD files come in a “wav.” container.

MQA: Master Quality Authenticated is a Meridian Audio proprietary audio codec founded by Bob Stuart for audio streaming and music download. It’s a lossless compression format that captures and stores original master recordings as files by a unique folding technique that is small and convenient enough to download or stream. MQA claims its tracks use a similar bandwidth to that required for CD-quality streams. MQA files can instead be packaged inside any lossless container such as FLAC, WAV, or Apple Lossless. To play MQA, you will need compatible hardware to unfold the high-res content, such as a music streamer or portable music player, or software such as the Tidal desktop app, to decode the MQA files. The non-unfolded mode will reproduce CD quality i.e., in FLAC format, 2X unfolding produces a Hi-Res definition of 24Bit/96kHz, 4X unfolding produces 24Bit/192kHz, 8X unfolding produces 24Bit/384kHz, and 16X unfolding produces 768 kHz, however, it is said that the file size remains the same because of the increased folding rate.

DSD (1-bit Direct Stream Digital): A one-bit format that uses the difference in pulse signal density to fit the waveform, so the sampling times are much higher than PCM. The sampling rate comes in 2.8mHz (DSD64 - SACD specification), 5.6mHz (DSD128), and 11.2mHz (DSD256) varieties, but due to its high-quality codec, and the amount of information continuously captured is also larger, it’s (mostly) impractical for music streaming. Theoretically, the definition of 1 bit in DSD is at least equivalent to 16 Bit 176.4kHz, but the accuracy is higher than 24-bit PCM.

FLAC (Free Lossless Audio Codec): This lossless compression format supports hi-res sample rates. The FLAC is compressed to nearly half the size of an uncompressed WAV or AIFF of equivalent sample rate, but there should be no “loss” in terms of how it sounds. It stores metadata and is royalty-free and a preferred format for downloading and storing hi-res music. It is not supported by Apple Music. FLAC files can also provide a resolution of up to 32-bit, 96kHz.

ALAC (Apple Lossless): It is an alternative to FLAC, although the files are slightly less compact than FLACs. 

WAV: developed by Microsoft and IBM is the standard format in which all CDs are encoded. It’s based on PCM (Pulse Code Modulation). It has great sound quality but it's uncompressed, meaning huge file sizes (especially for hi-res files). It has poor metadata support (i.e., album artwork, artist, and song title information).

AIFF: developed by Apple as an alternative to WAV, use similar technology as WAV, but store data in slightly different ways. It is lossless and uncompressed. AIFF can store CD-quality or high-resolution audio files with better metadata support (album artwork, song titles, etc.). 

WMA Lossless: A lossless incarnation of Windows Media Audio, but not well-supported by smartphones or tablets. 

Streaming methods

• Mobile phone or tablet - not recommended for hi-res direct streaming but maybe use instead to access and control music playback through the music player/streamer interface as a remote control that is gapless i.e., when you turn your phone or tablet off the music continues which means that the streaming is direct from the service provider, otherwise the music goes off suggesting that it is through your phone or tablet streaming the music i.e., music is compressed.

• Dedicated streamer - less noise than the computer, usually includes the music player interface, built-in DAC, more stable medium but costing much more. You need to ensure that your chosen audio player/streamer application can be applied to a streamer of choice. Further, you need to ensure that the streamer functionality plays Hi-Res audio e.g., MQA, DSD, PCM, or other preferred options. Many modern-day streamers offer pre-amp functions with digital volume control and multiple outputs with balanced options. 

• Computer (Mac or Windows) – windows should at least be i7 or better with an SSD hard disk. Try to use the maximum RAM allowable for your computer to easily run the music player interface and connectivity with the streaming service. USB outputs should support USB 2 or better for superior bandwidth when needed.

• There are many mini-computer designs (small form factor) with music streaming capability that is modular for noise isolation, power supply upgrades, connectivity upgrades (SPIDF), inboard or outboard DACs, etc. Single-board micro-computers are fast cornering the marketplace such as the famous Raspberry Pi etc. These are value add products because they can be stacked (HAT) with add-ons such as better power supplies, noise filtering, DACs, or SPDIF interfaces. Many other third parties such as Allo Boss and HiFi-berry among others make add-ons that are cost-effective to support the standard Raspberry Pi. Mini-computers are a better solution as a streaming device than the nosier standard computer and offer practical add-ons that improve sound quality.

A dozen recommended tips and tweaks

1. Use your present CD player as a transport only, provided there is a coax RCA output for a DAC. You could use a DVD Blu-ray player (or SACD) with USB inputs and use it as a transport only. Some Blu-ray Disc players provide both digital optical and digital coaxial audio connections. Most only provide one, and usually, it's digital optical so check before you buy.
   
   

2. Get a recent popular chip version with SPDIF coax or BNC inputs. The R2R topology I believe delivers a more natural sound. Dual mono chipsets for Delta Sigma designs are better than the single ones used.
   
   

3. A dedicated streamer is better than one integrated with loads of features that would be outdated with time. It’s cheaper and allows DAC upgrades. Make sure it supports hi-res audio when needed.
   
   

4. Decouple all components on a proper isolation platform, especially the CD transport.
   
   

5. Use Streaming services that have CD-quality streaming or better.
   
   

6. Junk the switch mode power supply that comes as stock, and upgrade to a linear power supply instead. This is the best upgrade you could do for your digital setup.
   
   

7. Download a good bit-perfect (input to output) audio-player interface for music playback.
   
   

8. If you are using the computer for streaming, use the stock computer battery for critical listening instead of the AC power supply or upgrade to a linear type power supply to mitigate computing noise.
   
   

9. You may want to consider a standalone ‘re-clocker’ device to get rid of inherent noise from the computer’s USB ports. Use a USB 2 or better-ready output to re-package the data before going into the DAC.
   
   

10. A dedicated DAC without headphone application (DAC amp) is better as the manufacturing cost would go into the business end of the DAC which is the chip and D to A circuitry and not the built-in amplifier to drive the headphones. Moreover, the additional circuit provides the potential for noise.
    
    

11. Avoid fancy light display panels or choose one that can be switched off, this additional circuit provides the potential for noise.
    
    

12. A mini-computer such as the Raspberry Pie as a music streamer is preferred because it is less noisy and cheaper with the potential for great add-ons. You can have your choice of DAC and other useful upgrades for better sound quality.

Conclusion

The compact disc with all things being equal has better sound quality than the present-day streaming services even if you intend to stream Hi-Res music files. This is because a version of the reference master is tailored according to the streaming service’s technical specifications that may require some form of compression. Therefore, they are all not going to sound the same and you will not know which version of the master you will be getting. So don’t be too quick to discard all your CDs but instead rip them to your hard disc ensuring bit-perfect transfer and archive a copy in case your hard disc crash or is damaged. You need a powerful lossless CD ripper application for this. You should consider a CD or Blu-ray player as a transport with an outboard DAC that will provide better sound quality than any music streaming service at this point. I believe streaming services will get better, until then, you will be wise to get an SACD-ready player and a DAC that is compatible with all the hi-res music formats out there. If digital is your only source for music playback, then you should get the best possible DAC you can afford based on the budget suggested in the budgeting article.

Questions?

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dennis@hearasia.com

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