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Review & Measurements of Allo DigiOne Signature and DIYINHK Pro3Z

amirm

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#1
This is a review, detailed measurements and comparison of two S/PDIF digital audio output converters. The Allo DigiOne Signature is a networked S/PDIF converter built on top of Raspberry Pi single board computer. It retails for $239. With the nice acrylic case, it goes for $259:

DIGIONE SIGNATURE PLAYER RPI SPDIF converter review and measurements.jpg

The benefit here is that you can convert any DAC with a S/PDIF digital audio input into a networked DAC. You can place your remote computer/tablet anywhere and have it stream the audio to the Allo DigiOne Signature where your audio system is. The above price does not include the Raspberry Pi which you have to add for a functional system (about $35).

My test system came with "DietPi" packaged Linux distribution for RPi which makes the unit turnkey with native support for Apple Airplay and Roon (RAAT) protocol. As such, I was able to simply power the unit and start playing files to it from my favorite audio player, Roon.

The DigiOne Signature requires two power supplies: one for RPi and one for the Digione Signature. I powered the RPI with the supplied switching supply from Allo and used my sbooster linear power supply for the "clean" power. Both inputs are UBC-C connectors.

In comparison, the DIYINHK DXIO PRO3Z is a USB to S/PDIF converter. It retails for $299 usually but I see it on sale as of this writing at $217. It is on a kind loan from a member:
DIYINHK DXIO PRO3Z USB to SPDIF converter Review and Measurements.jpg

As you can kind of tell in the picture above, despite the attempt to make the unit seem high-end with that gold color, the unit screams "DIY" and low-end. Mind you, it works but it just doesn't give you something you would want to look at all the time. :)

The unit did not with an external power supply but does accept one as you see in the above picture. For my testing, I just used the USB input for power.

The main use of PRO3Z is to add USB functionality to older DACs without this input or improving the performance of the ones with poor UBS implementation.

Let's get into measurements and see how they both did.

Measurements
My APx555 audio Precision analyzer has a complete subsystem for analysis of digital input interfaces. I have not shown this capability before so I thought I do that in this review. For this testing, I used Roon to play the J-Test signal at 48 khz and then measured the spectrum of jitter using a high-resolution FFT. I also measured the APx555's own S/PDIF output as a reference. Here is where the chips fell:

Allo Signature SPDIF and DXIO Pro3Z Jitter Measurement.png


The graph in green is the S/PDIF output of APx555. It actually has more spikes in the audio band than the other two in part of the spectrum. However, their amplitude is is extremely low at just 1.6 picoseconds and lower.

Allo Signature is in blue. It has a spike at 12 kHz that goes up to 4.3 picoseconds or so. Otherwise it has a very clean noise floor, sans some mains related spikes at lower frequencies.

DXIO PRO3Z performs similarly as far as noise floor but has a spike at 24 kHz (half the sampling rate at 48 kHz). and more sidebands where the main tones are (again, likely related to mains leakage).

Of course, the whole graph is a practice in "measureabating" where we are digging so deep to find anything. In more ways than one, we are showing off how sensitive our measurement systems are. To wit, the DigiOne Signature has a BNC input in addition to RCA. Comparing those two inputs, we are able to tease out their performance differences:

Allo Signature SPDIF RPI converter BNC vs RCA Jitter Measurement.png


The BNC output (in purple) is "considerably" cleaner due to better impedance matching. If you have BNC at your DAC, I suggest using a BNC cable to connect both.

The measurement was so sensitive that my standard SPDIF cable that goes from BNC to RCA showed substantially more jitter components than above!

But again, this is mostly an educational experiment than anything to do with audible distortions.

For that, let's see how these two act when driving a rather poorly implemented DAC, the Schiit Modi 2 Uber. This DAC is sensitive to jitter on its input (filters very little of it). Its USB input is not good either as we see here as a reference:

Schiit Modi 2 Uber Jitter and noise Measurement.png


Anything other than the main spike at 12 kHz is distortion, noise and jitter.

Let's drive it now through its S/PDIF input with Allo Signature and DXIO PRO3Z:

Allo Signature SPDIF RPI converter schiit modi 2 uber jitter and noise Measurement.png


We see identical performance from both, substantially lowering the jitter and noise products from Schiit Modi 2 Uber. What is left from prior testing, is due to deficiencies in the rest of the Modi 2 Uber DAC than anything to do with digital input jitter.

Conclusions
Allo DigiOne Signature and DIYINHK PRO3Z both provide very clean S/PDIF outputs. While the Allo outperforms it a bit at micro-level, there is really no fault here to worry about. Between the two though, the Allo is much more capable from functionality point of view since it has built-in networking (with the addition of required RPi board). That, and excellent performance gets Allo DigiOne Signature on my recommended list.

The DIYINHK works well but it is too expensive. You can buy a DAC for this price with just as good of a USB input. If this was a few years ago, sure, there would be a need for this when USB input was less common. Still, this may be a cheaper option for some to get better USB such as on Schiit DACs that don't have their "Gen 5" USB input. For a much cheaper option, you could look at Topping D10 which is a DAC but also has S/PDIF output.

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#2
Hello Amir

again , thx you very much for your dedication and impartial testing of our and others hardware .

I would like to explain a few things on the RCA output. The standard on coaxial is 75Ohm , unfortunatly RCA connectors and RCA cables are not capable of 75Ohm because of geometry/physics . We spoke to a few manufacturers of DACs and some of them already implemented 50Ohm impedance (since 75R is not possible) . Basically instead if doing text book , blind implementation , we take in consideration real world impendances and with a good DAC manufacturer 50R will be implemented on the RCA coaxial input

I know there is one manufacturer that claims 75R on the cable (I think its canari cables) but still your connectors will be 50R thus defeating your cable impedance.

What you see on BNC is the right implementation as per the standards. 75Ohm all the way since cables and connectors are designed that way.

Overall I think that Signature and AP machine are pretty close (especially on the BNC). That makes us very happy as AP machine is the standard in the audio world
 

Veri

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#3
I know there is one manufacturer that claims 75R on the cable (I think its canari cables) but still your connectors will be 50R thus defeating your cable impedance.

What you see on BNC is the right implementation as per the standards. 75Ohm all the way since cables and connectors are designed that way.

Overall I think that Signature and AP machine are pretty close (especially on the BNC). That makes us very happy as AP machine is the standard in the audio world
Very interesting. So basically because of the connectors, 75-ohm RCA falls into the "snake oil" category?
 

amirm

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#5
Hello Amir

again , thx you very much for your dedication and impartial testing of our and others hardware .

I would like to explain a few things on the RCA output. The standard on coaxial is 75Ohm , unfortunatly RCA connectors and RCA cables are not capable of 75Ohm because of geometry/physics . We spoke to a few manufacturers of DACs and some of them already implemented 50Ohm impedance (since 75R is not possible) . Basically instead if doing text book , blind implementation , we take in consideration real world impendances and with a good DAC manufacturer 50R will be implemented on the RCA coaxial input

I know there is one manufacturer that claims 75R on the cable (I think its canari cables) but still your connectors will be 50R thus defeating your cable impedance.

What you see on BNC is the right implementation as per the standards. 75Ohm all the way since cables and connectors are designed that way.
Hello Johan. Yes, this has been talked about a lot before but I had not seen measurements of jitter with it in audio products until I did this test.
 

nbpf

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#6
Thanks for the measurements but I am not sure what kind of conclusions can be drawn from them. Perhaps it would have been more relevant to compare the DigiOne Signature to the standard DigiOne as many users of the standard DigiOne might be considering to upgrade. Or perhaps to compare the DigiOne Signature and the DIYINHK Pro3Z to a device that you consider to be a reference device? I might be missing something, of course.
 

Blumlein 88

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#7
Using your never before seen here on ASR picosecond graph, it would be nice to add some other gear for perspective and reference. Maybe the Audiophilleo. Maybe a couple of the Topping DACs, the Auralic and the RME DAC. So we can get an idea how such things run between various bits of gear.

Summer is pretty much over anyway, so what else have you got to do other than some additional measurements for the rest of us? :p
 

Nango

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#8
Thanks for the measurements but I am not sure what kind of conclusions can be drawn from them. Perhaps it would have been more relevant to compare the DigiOne Signature to the standard DigiOne as many users of the standard DigiOne might be considering to upgrade. Or perhaps to compare the DigiOne Signature and the DIYINHK Pro3Z to a device that you consider to be a reference device? I might be missing something, of course.
Why upgrading? .... as you are not going to hear the difference (in jitter terms at least) ??
 

Jimster480

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#9
"Both inputs are UBC-C connectors. "
-Likely you meant USB-C?

"poor UBS implementation. "
-Again here I imagine you meant USB :)

Great review as always, but as Blumlein said its hard to draw any conclusions from your picosecond graph with no other test subjects :)
 
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#12
I do not know, but many DigiOne owners seem to have bought a DigiOne Signature or considered buying one.
It's noteworthy that the non-signature model is still on sale at a much lower price than the Signature. One might be tempted to consider whether the problem with the non-Signature model was that it was too cheap. If the original model was any good at all then its performance should be very close to the signature.
 

Purité Audio

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#13
I am going to order the ‘katana’ and ‘digione’ looks a really nice bit of kit, I will get the son and heir to road test it ,
Keith
 

Purité Audio

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#15
He won’t be getting much a large pair of black horns...
Nice to see you here, assuaging the Mdac pain?
Keith
 

Purité Audio

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#17
Likewise, I have been following your contributions on CA, as part of my 24hour surveillance, they aren’t much of a challenge though are they?
BW Keith
 
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#18
Likewise, I have been following your contributions on CA, as part of my 24hour surveillance, they aren’t much of a challenge though are they?
BW Keith
It's an interesting place. Big difference between General Audio which is about typical in balance, and the other sub-forums where anything less than 4 usb-usb converters each with a battery pack and an entreq grounding box is considered mid fi.
 

Veri

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#19
It's an interesting place. Big difference between General Audio which is about typical in balance, and the other sub-forums where anything less than 4 usb-usb converters each with a battery pack and an entreq grounding box is considered mid fi.
Don't forget about the interconnects and power cables.
 
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