Review: Allo DigiOne Signature Player

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Wietsche

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Allo DigiOne Signature Player




Introduction:

I received a surprise package in the mail a bit more than a month ago, all the way from Mumbai, India. I immediately knew that it was sent to me by Allo.com as the package looked almost identical to the Katana I received some weeks before. To my surprise there was the latest and greatest DigiOne Signature Player, fully assembled, neatly packed inside. I personally own the original first generation DigiOne that was my first purchase from Allo.com and was very eager to compare them to hear if there can really be more improvement to what I considered already an excellent Coax SPDIF transport. I took my time with this one and put it through its paces; here is my review of the new DigiOne Signature from Allo.com.

The headings are clear and if you are familiar or an expert on some of the topics, please feel free to skip ahead. I tried to cater for readers of all experience levels.


What is this DigiOne thing, and what does it actually do?

The DigiOne products from Allo.com are meant to provide the user with a high-quality digital audio SPDIF output signal, that needs to be connected to an existing external high-quality Digital to Analog Converter (DAC) via an RCA or BNC coaxial digital audio cable. Thus, the output of the DigiOne is not analog audio but still in the digital form and needs to be converted to something you can amplify and actually listen to. Much like what a traditional CD player does when you use the digital audio output signal to your Home Theatre AVR or integrated amplifier. Except now, the digital audio source is not a spinning disk, but a digital audio file served up with a Raspberry Pi single board computer (SBC), converted by the DigiOne hardware to the same SPDIF signal that the CD player would have provided. So, the DigiOne is not a DAC but just a transport, and brings the signal to your DAC.

This enables you to play your massive collection of computer audio files to your HiFi from a low powered, acoustically silent palm size computer. There are many similar devices that can do the same, even your phone, but the focus here is on the audiophile?s needs with little to no compromise on audio quality from the source and upwards, and this gives you the flexibility to choose your own high-end DAC for a more modular system.

In a neat, small and pretty enclosure, you get the Raspberry Pi computer and the DigiOne add-on component boards that is plugged in directly to the Raspberry Pi. The DigiOne receives a data signal from the Raspberry Pi at the bottom and works its magic to deliver an astonishingly good measuring SPDIF digital audio signal that you can feel confident about and feed that to your high-end HiFi equipment that you cherish so much.

To achieve this high-quality signal, timing of the bits needs to be precise and there must be little to no other electrical noise mixed in with the signal that could cause distortion or confusion within the DAC. The latest iteration of the DigiOne product line, the DigiOne Signature, does this in a number of ways. To reduce the noise and get clean power supply, they have separated the power of the Raspberry Pi and the DigiOne Signature by providing two power input jacks to take separate power supplies, one for the ?clean? side and one for the ?noisy? side. Where the Pi and the DigiOne Signature boards needs to interact, they have implemented the hardware to galvanically isolate the ground and signal conductors between them. There is also a super capacitor that deliver immediate power as needed from its stored energy without needing to ?fetch? power from the plugged-in power supply. They have gone further to discard the data clocking from the Raspberry Pi, and then re-clock the data signals received by its own high quality onboard NCK clocks to ensure ultra-low jitter (Allo claims less than 400 femtoseconds) timing of the bits that are sent to your DAC. There are more technical details given in the DigiOne Signature manual. In essence they strived to reconstruct the digital audio signal in the purest and accurate way possible and still provide value to the customer.

Please take note that when the word ?Player? is attached to an Allo product, it means that you are getting an all-inclusive kit, containing everything you need to get going. So, I got the DigiOne Signature Player. When you look on the Allo.com website, you can also find the DigiOne Signature (without ?Player?) and that is just the add-on component board, and you have to provide your own Raspberry Pi, SD card, power supply and enclosure to make it work as intended. The exception to this is the USBridge product that is also an all-inclusive kit, but where the DigiOne provides SPDIF output, the USBridge provides an audio grade USB port for your external DAC to connect to.






Explaining the integrated Raspberry Pi computer:

I think the main reason for using a Raspberry Pi instead of a full multifunctional general computer is the ability to strip out all the useless software from the operating system and only leave the essential core functionality in place and make it fit for purpose. This is usually based on some variation of the Linux OS. There are so much going on in the background on any Windows, MAC or Linux full desktop operating system that has absolutely nothing to do with processing music. With a bare minimum system, you can allocate all the resources towards your audio processing functions, and also switch off anything else not being used, and enable these low powered computers to excel at audio processing without breaking a sweat and be super responsive and reliable. They use so little power that you can leave them switched on all the time and be ready and waiting for your command.

The best part of all is that these compact purpose-built systems are ready to download and use immediately with very little effort or knowledge needed to get it working. Most of the time it involves loading the system onto a SD card, plug everything in and powering it on, and then wait and follow the instructions on a web interface. These systems are usually developed and well documented by users, for users. The Raspberry Pi online community is very large and very helpful.

The Raspberry Pi has no moving parts, which means it makes no acoustical noise and generates less electrical noise. It has everything you need built in as standard, especially the latest version (V3 B+ at time of writing) that has dual band WiFi AC and Bluetooth 4.2 built in. Nothing else is needed to be plugged in to do all you need. And then it uses very little power and run from a 5V source.

The Pi is MUCH smaller than any full-sized computer and fit in the palm of your hand and can be managed remotely from another device or your smartphone without a screen or keyboard/mouse attached to the Pi, significantly reducing clutter and complexity with your HiFi setup.

Another big reason for using a Raspberry Pi is that it is MUCH cheaper than any full-sized computer. There is not much to lose. When you are done with your current implementation of the Pi for some reason, the Pi can be repurposed for a range of other projects and not become redundant hardware. Its functionality and behaviour are largely determined only by software. One usually only need to load a new system on a SD card and configure a few settings for the Raspberry Pi to do a new job.

The moment you put the Raspberry Pi in the mix, you have endless options to choose from regarding how and where the Raspberry Pi gets the music files from and which software it uses to play the files. It enables you to do all you did before with less/smaller hardware, more efficiently with more flexibility, and even opens up options you have never even considered before. For a small cost you add all these features to a product like the DigiOne Signature and it takes care of everything from obtaining the music data to converting it for you into a high-end signal for your HiFi. Integrating a Raspberry Pi into a product like the DigiOne makes a lot of sense now, doesn?t it?

 


Software and Operating System choices for the Raspberry Pi.

Choosing software and an operating system for your Raspberry Pi is  a very subjective choice. I will only mention the 3 options that I know well and used to test the DigiOne Signature. They are all free software, with ready to use SD Card images.

My personal view is that it does not make any difference which music playing software or system you choose to run on your Raspberry Pi, as long as it is properly developed and configured for audio playback and supports your hardware, the music sounds the same or is not even worth debating. The choice should be mainly based on what functionality you want and how it needs to integrate into your existing systems and hardware.

Then you need to decide if you want to play files from your home network (using WiFi or a LAN cable) that are hosted on a file server or NAS, or stream music from the internet, or have no network connection at all and store the files locally on USB storage or the internal SD card. Of course, you can have all these options available at the same time as well. It is usually dependant on the user?s configuration.

Based on the above prerequisites that you have established, you then choose a suitable Raspberry Pi system to download, copy it to SD card, start it all up and then configure it towards your needs.

I use PiCorePlayer to simulate a Squeezebox Player that plays files from a dedicated networked media server that hosts Logitech Media Server (LMS). This way I keep all the hard indexing and file management work away from the Raspberry Pi making it even more lightweight to run. It only needs to receive the data from the network and play it. This even works well on older generations of the Raspberry Pi and the Raspberry Pi Zero. PiCorePlayer is usually ready in 15 seconds from powering it on.

I have also used Volumio in the past, which works like a Squeezebox, supports DLNA/UPnP, and has a rich web-based user interface. Volumio can also be a standalone player that plays locally stored music files and hosts its own music library, and it can play internet radio stations as well. In the past I was not happy with the performance of Volumio with huge music libraries, but they have come far with their development and the faster Raspberry Pi 3B+ runs it very well. I?ve used it 50% of the time for this review to get a good feel of the latest version and I am very impressed with it. It starts up and will be ready to use in about a minute.

A third option is DietPi and this system is totally flexible and the user has to choose from a huge list of abilities with the initial setup. It will then install everything you selected for you automatically and ask for user input when needed. It supports DLNA/UPnP, Roon endpoint, Squeezebox and LMS, and much more, even your 3D printer with OctoPrint..but that is going off topic now. I used DietPi the least so far.

The above should get you started. But there is a HUGE community on the web with lots of helpful info and opinions. Google is your friend from here on forward.
It?s good to experiment with the different options if you have no experience or exposure, and eventually you will settle on a minimalist configuration that gives you the best experience and reliability for your setup and needs.

Now, let?s move our focus to the actual product.



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