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:
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:
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:
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:
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:
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:
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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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:
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:
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:
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:
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:
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.
-----
If you like this review, please consider donating funds using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
