ALLO BOSS, PIANO 2.1 DACs with RPI, SPARKY, KALI & the VOLT Amplifier [REVIEW 2016]

In 2016 I was using the IQAudio DAC+ for quite some time and found it to be really quite astonishing for such a small unit. It was the first DAC I used in conjunction with the Raspberry Pi. But then along came ALLO.  The latest ALLO unit at that time was the PIANO 2.1 DAC. It also used an SBC (single board computer) which was a different build construction to the RPI called the Sparky.


Let's unbox


As you can see, very nicely boxed.


The ALLO SBC is called 'Sparky'.


As you can see, it's quite similar in looks to an RPi board.

The thing that makes the ALLO audio streamer different to the IQAudio is the re-clocker board called the 'KALI' which irons out any jitter. This is a HAT board of which fits on top of the Sparky SBC.

You also power through the KALI and not through the SBC.


Here are some specs:

The basic design includes FPGA based FIFO board
I2S input: 44.1 KHz, 48 KHz, 88.2 KHz, 96 KHz, 176.4 KHz, 192 KHz - 16bit, 24bit or 32bit
I2S output: 44.1 KHz, 48 KHz, 88.2 KHz, 96 KHz, 176.4 KHz, 192 KHz - 16bit, 24bit or 32bit
FIFO Memory: 4MB SRAM
Can be used with external Crystal Oscillators for MCLK or upgraded to a higher quality, a multi-frequency clock that comes with automatic Fs switching and better performance
LED indicators (Power, Full, Lock, Empty, Sample Rate, Mclk)
DC power supply: (5V/3A) with Filter circuits
Multi-frequency output capability to support the full I2S working range from 44.1 kHz to 196 K
Automatically switching frequencies according to the input I2S signals
Extremely fast and very low propagation delay Flip-Flops are added on I2s signals output from FPGA, for synchronization with MCLK before sending to DAC
Ultra-low-noise voltage regulators for optimal audio performance
Integrated EEPROM for automatic configuration (with write-protection)

Then on top of that comes the 'PIANO' and in this case v2.1. The Piano board is the DAC and is where you will find the audio outputs.


You will probably notice that it has x4 outputs. Two outputs are for stereo out, and the other two outputs are for a sub-woofer stereo out.

Here are some specs:

Dedicated Two no’s of 384 kHz/32bit high-quality DAC PCM5142 for best sound quality
Available with different output connectors: 4 x RCA
DAC SNR is 112dB
DAC THD+N @ - 1dBFS are –93dB
Full-Scale Output of DAC is 2.1Vrms
Dynamic Range of DAC is 112dB
Sampling Frequency ranges from 8 kHz to 384 kHz
Ultra-low-noise voltage regulators for optimal audio performance
Integrated EEPROM for automatic configuration (with write-protection)

The fun doesn't stop there either... Yup, you have guessed it, there is another board to go.

The next board that fits on top is, of course, the amplifier. The amplifier is called 'VOLT'.



Here are some specs:

This class D amplifier goes up to 2 x 50W Max
The components used are specifically designed for high-end audio devices (Würth Inductor, TI chipset, film capacitors and ± 1% thin-film resistors)
VOLT AMP boasts 4 output filters, 4 EMI Snubbers, 4 bootstrap capacitors and gain setting components And Additional Provision for stepped attenuator volume control

Technical Specifications
Chipset: TPA3118D2
Output: 2 x 50W (Max) into a 4 to 8-Ω BTL Load
Class D Operation: 90% POWER EFFICIENCY
SNR: 102dB
Supply Voltage: UP TO 24V DC
Board Size: LWH = 58mm* 86.75mm * 32.06mm
Temp Range: -40°C to 85°C Ambient

ALLO have really gone to town on this design as a system in its entirety because there is one more board to go. The PSU for the VOLT called the CAPACITANCE MULTIPLIER


Some specs here:

Max Vin (30v)
Min Vin (6v)
Dropout voltage is trim pot selectable from 0-3V (dropout voltage should be always higher than ripple/noise of PSU)
Factory default is 0.5V
Power dissipation is dropout Voltage x A used = W of heat
PSRR of 70db
This circuit is very suitable for class A and class D amplifiers or even to feed clean power to your SBCs

So altogether we have a superb little system here and I have to say it really does sound very nice indeed. The system also comes with two acrylic platforms for assembly too.

As for ease of assembly, it's really very easy and only takes 5 minutes.

Here are some pics of the assembly process.






So, lets get on with how this sounds. (No Veils or blankets were used in this review)

I am reviewing this only two days into hearing it for the first time using the SPARKY, KALI and Piano 2.1 boards in comparison to the RPI 2 and the IQAudio DAC+. Not a long time in I know but it's long enough to give you something to think about. Also, I am not using the supplied wall-wart PSU as I use the SBooster BOBW PSU which is great because it comes with a selection of connectors. 

So before we start I have to say that at this moment in time there are still some software bugs that need to be ironed out. But this is quite understandable. The hardware however is solid.

This system uses MAX2PLAY for its user platform and can be used with Squeezelite, Share port (Airplay) as its user interfaces. In this case, I'm using Squeezelite as I have a USB drive connected and not a NAS box system.

The Sound:

The first thing I noticed was the amount of information coming through. Lots of detail which I have to confess I knew was there but it's never shown itself as clearly before now if you know what I mean. Because of this, the stage is wider and deeper with lots of air. You can track instruments much easier.

The second thing I noticed was the bass. From when my dub track kicked in it made me smile. This is proper bass. Listening to lots of different tracks from different genre's the bass comes through easier with more definition and focus creating a much more realistic mid-range fluidity.

From this moment in testing and in comparison to the IQAudio/RPi combo, I think the ALLO most certainly comes out the most focused. But... the IQAudio does have a certain something which is more of a relaxed presentation. These are early days and I will be returning to the IQAudio/RPi system at a later date.

Now let's power up the VOLT!

The Volt has up to 50wpc output which is really quite enough for most.

I hooked up my 15" Tannoy Monitor Golds and away, way, way-we go!

Very impressive... for something that's so small this has to be the best digital amp I've heard. My speakers are not hard to power, far from it. So this may vary with different speakers but I have to say I'm very impressed indeed.

I'm going to keep this review open so I can keep on updating on how this opens up over the next few months so stay tuned.


Enter the BOSS

The next stage in this thrilling story is the next addition from ALLO. This is called the BOSS.

Doing away with the Piano 2.1 and KALI cards, the BOSS takes on both of those cards in one. Also, for better stability, I also returned to the RPI.

So, moving away from the Sparky/Piano/Kali configuration, I let the BOSS run in the system for a good few days and what can I say... very, very nice indeed.


One thing I found overusing the KALI/PIANO 2.1 combo was that the transient details have been improved for certain. For example, one of the reference albums I use is by Shpongle. With lots of focused and dynamic bass and oodles of transient effects. On one track there is a water drop style effect. This with the KALI/PIANO was great but with the BOSS in charge, there is a noticeable improvement in space and depth.

On other albums like Muddy Waters, The Beatles, Goldfrapp, PJ Harvey, Teenage Fanclub, Ride, The Rolling Stones, Lemon Jelly, Iron Maiden, I found the improvements the same, drums seem more fluid and the timing is simply stunning.

The bass has again been improved in dynamics. It has more kick with more air making it that little bit more realistic and not overzealously fatiguing. With the mix of improvements in timing and nano resolution, this little baby really puts a grin on your face.

There is certainly some wizardry here and it's most certainly the best sound I've heard so far in the RPI configuration. This is moving towards a very analogue sound, and (dare I say it) a very 'vinyl-like, with a natural presentation with no real harshness. There are no horrid aspects to what I can hear that you can get from some DAC's.

All in all... I find it's a very nice improvement over the KALI/PIANO combination. I don't listen to much classical and if I do it's mostly on vinyl but I do love ambient music, acoustically or digitally created so I find this to cope well with very delicate passages but on that note, I do find the IQAudio's tone slightly more attuned to this over the BOSS and the KALI/PIANO.

The BOSS makes me think about what we are all trying to achieve with digital and for me, it's both accuracy and drama to which some DAC's (RPI based or otherwise) can give an uneven keel on presenting.

Quite respectively on balance, the BOSS has it. It's a little gem of a DAC.

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