Allo Boss DAC review


(Janis) #1

I had today opportunity to test the new Allo DAC Boss. It is another great product from Allo @allo.com , and in my view has three interesting differentiations:

First of all, it has such a deep, deep, low, juicy bass flowing out and projects powerful sound stage!
According to Allo the foundation for this unique performance is the Supercapacitor of 0.22F…!!! you see in this picture. I personally would have given to this DAC product name “Bass" not “Boss”…
:slight_smile:


Second, notable differentiation is very low noise floor. On 0dB volume the Boss is almost completely silent. While I can hear some 50Hz noise from Kali+Allo DAC, and quite high 50Hz and to shielding sensitive high frequency noise from Audiphonics 9018K2M DAC.

Finally, it is a master DAC. It has two high quality clocks (44.1 and 48 kHz) on the board running not only the DAC itself, but also sending accurate BSK clock of 44.1 or 48 kHz (depending on the music encoding ) to Raspberry Pi, based on which then Raspberry Pi is timing LRCLK (frame) & Data and in return sending both back to the DAC trough i2s. The result - reduced jitter! I my hearing not as low and accurate as Kali+Allo. However, the two 44.1 or 48 kHz master clocks enable extremely low jitter level for this budget DAC, and result in much better sound quality than majority of slave DACs feeding from the single inaccurate Raspberry PI clock.

Now here is my scoring of Allo Boss vs. the two best Raspberry Pi DAC alternatives in the market currently - Allo Kali+Piano and Audiophonics 9018K2M.

While above differentiations clearly make this DAC to stand out with the best bass and lowest noise floor. In my subjective perception the sound reproduction dynamics, accuracy, and transparency is not as good as other two top DACs, and voice presentation in vocals is not ideal.
While mens vocals get good lower tones and deeper voices, they are bloated and washed together with lower frequencies; thus, lacking clarity and separation. Even more noticeable it is for women vocals, where voices besides being bloated and washed together with lower frequencies, are getting unnecessary lower tonality mix-in and shift. Here Audiphonics is standing out and leading the crowd with by far the most natural, best presented, and accurate voice reproduction. Also Kali+Allo combination is also better sounding that Boss.

My subjective conclusion.
Allo Boss is by far the best quality entry level DAC in the market competitively priced at 59$ vs. HiFiBerry, IQaudIO, etc.
However, it is not as good as the two best more expensive alternatives - combination of Allo Kali + Piano at 120$, or Audiophonics 9018K2M at 110$.
I think Allo Boss is ideal DAC for general public and specially bass lowers, Allo Kali+Piano for Pop & Rock lowers, and Audiophonics for Vocals aficionados.
:blush:

P.S. @Dan_Knight just has created 192 kHz drivers for Boss on DietPi in the development set-up. They work perfect, but need to be enhanced for 384 kHz playback still, and populated in the next public version kernel.


Is my AVR DAC good enough or should I buy an external DAC?
(johan ) #2

Hi Janis ,

great review . I laughed when you said it should be called Bass instead of Boss :slight_smile:

Yeah for sure it has great bass , its because of the supercapacitor. You see , bass need more electrons than hi frequency so 0.2F of electrons was just what the doctor ordered.
I am a bit puzzled about your mid/hi frequency findings . Again what we did is used SMD film capacitors , usually that gives very good separation in those areas. In fact in our testing with AP machines we have better THD+N on Boss than Piano…however just by 2db.

Its possible that your unit will open up more since film capacitors , unlike ceramics need a “burn in” time of aprox 50h of playing music. So it will be interesting to know if you see any improvement.
A second reviewer is talking about the Boss being much better on timing and resolution http://theartofsound.net/forum/showthread.php?46809-The-ALLO-Audio-music-steamer-Pic-heavy-review/page25 , I am trying to find out how many hours she played on the unit. The difference might be "burn in "

Our Boss is designed to be a very good entry level DAC with sensible pricing and good performance. Note that is half price from Kali/Piano combo. Of course Kali is more versatile and can be used with any DAC.

Its all about the music in the end. Enjoy.


(Edward) #3

Usually I find that when a components sound is skewed in one direction or has some overwhelming pronounced sound, its not broken in.

I’d give it a few weeks and see if it opens up.


(Janis) #4

I now put burn-in track to loop on it, and will test next week to see if/ what are changes in SQ.
Will report back to all here.

However, I had it already playing for at least 36 hours non-stop before I tested.

Janis


(Edward) #5

200hrs seems to be the magic number for burn in…


(Mr Fix It ) #6

Why does everyone talk about burn in improving everything… what about burn out? :sweat_smile: I personally don’t think the electrons care. I can understand it might sound different but an improvement always seems to be the basic assumption. I don’t buy it’s always an improvement. That’s just my engineering mind.


(Edward) #7

https://sites.google.com/site/computeraudioorg/cable-break-in

Burn in theory, tell me what you think…

FYI Audioquest explains something similar about their wire


(Alex Bartels) #8

Hi Edward,

Totally agree!

In my opinion, even after soldering wires or components, it needs new break-in / burn-in…
Even in mains section or psu section. Difference is VERY noticable. Normally I take 150 Hrs as rule.

Sometimes audio components just act as a very good bottle of wine :slight_smile:

Regards,
Alex


#9

Haha, if it really ‘burn out’ than you got a reliable issues, can send back and get a new ones😀! Actually the main component in the electronic circuits that requires burn-in is mostly the capacitor. These guys are chemically bonded with two electrodes, one positive and the other negative. When a voltage is applied to the capacitor for a period of time, the chemical reaction inside the capacitor becomes more stable. Once the stability has reached, the performance of the capacitor will peak over its lifetime until the chemical inside the capacitor start to degrade, then it is time to change.

Big caps like the ones use in power supply are notoriously hard to burn-in because of its sheer size. Burn-in approximately less than 100hrs are quite common but some can go up to 300hrs. One will hear the sound improvement as it go along until no improvement is observed.


(johan ) #10

On our film capacitors we ask 50h of burn-in (small surface). Janis is burning his unit as we speak. Lets see if (any) improvements are detected .


(Janis) #11

I did today retesting of the Allo Boss DAC after 4 days non stop burning-in with looping burn-in track.

Yes, there is overall improvement, very positive impact on mid-low, but no improvement in high frequencies.

Overall: even greater dynamics and presence, richer audio reproduction, and better segregation of different frequency sounds

Mid-low: much better natural, deeper and solidly round voice that now is less metallic that Kali-Piano combination (was opposite in beginning), as well disappeared the washing-off of voice with low frequencies

High: no real improvement here, Boss is still missing presence of high frequency reproduction, it is also sounds less transparent, and less accurate that Kali-Piano combination

Also I compared once more with Audiophonics 9018K2M, but only on 24bit, as it has quite audible high frequency distortions on 16bit playback, even with all extra wiring and serial drive of ALSA synchronization. Audiophonics has still the best natural and velvety voice, but less dynamics and bass, as well is somehow in the middle between Boss and Piano in high frequency reproduction.

Summary:

  • Boss is the best price performance DAC, and I think especially good for Rock, Rap, etc.
  • Kali-Piano is the best high frequency DAC, great for Pop
  • Audiophonics 9018K2M is the best voice DAC, good for vocal and classical music, but unfortunately it doesn’t work with 16bit music files, unless up-converted by Roon DSP and then not bit perfect

(johan ) #12

Talking about “golden ears”.

Basically there is a subset of people that can hear small details that usually escape most people (like me for example). Janis has those…

Not happy with the feedback of "mid to hi frequency reproduction problems " from above , our engineering team has taken the BOSS and started reviewing it from the top. We started with the filters , LDOs , Oscilators …nothing. Ground was checked , jitter , again nothing.

At last we arrived at low pass filter in the end of the analog signal. On the Piano TI has in the datasheet a LPF with 73Khz cutoff, in the new datasheet they have it at 150Khz (so different resistors and capacitors). What we did, is we took the old capacitor value and added the new resistor to it…basically a cutoff frequency of 16Khz (-3db). From 8-20Khz the LPF is introducing noise , instead of cleaning hi frequency noise thats above human hearing(but still can distort the audio)

We are rushing now, testing the unit with the right values and sourcing in time for mass production.

I am now a firm believer that Janis has " golden ears"…


(STEPHANE L) #13

Will the Boss DAC work with DietPi?


(johan ) #14

Yes it will


(STEPHANE L) #15

:+1:

Thanks for the prompt reply


(Michel Picard) #16

Great review @Janis , and it’s awesome to see that @allo.com reacts and tries to improve the Boss before mass production :+1:
I can’t wait to read an update by @Janis with this new improved version.

BTW, I’d really love to read a comparison between the HifiBerry DAC+ pro and the Piano Boss. If I understood correctly they both use the same DAC chip, but with a radically different board integration…

Again, thanks for this great review.


(Andy Spinks) #17

So did the LPF get fixed in the production version of the Boss?


(johan ) #18

yes it did, we are shipping corrected versions to reviewers and customers since Friday . Expect feedback this week .


(Henry Larsen) #19

The boss was tested with an RPI, right? Considering to buy it, would it make any difference to go for the Sparky instead of an RPI 3 for it?


(johan ) #20

The BOSS as a master DAC only works on RPI