What Audio Server Sounds The Best?
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What Audio Server Sounds The Best?

Which audio server sounds the best? This is one question I get asked a lot and
I could simply say that when the server hardware is sufficiently powerful, there is no difference. But how come people do hear differences? The first reason might be the use of a normal
computer to drive a digital to analogue converter directly for this is far from ideal. For one the clock that drives the output is
always influenced by other clocks in the computer, this is the worst for SPDIF or optical since
it is a isochronous signal that needs to arrive at the DAC at a precisely timed intervals. For USB this is less of a problem since USB
audio nowadays is asynchronous, so sent in packets. But both USB and SPDIF suffer from pollution
of the ground plane. As you will understand, if the ground is polluted,
the voltage between that grond and the plus will vary, meaning that the non perfect square
waves that represent the bits will be shifted slightly, varying the way the receiver chip
in de DAC defines the exact time a bit passes by. See my video “Connecting your DAC #2: how
digital can go wrong”. Due to safety regulations it is not possible
to fully disconnect ground unless we use optical cables and those have a limited bandwidth
and thus have limitations of their own. So what we would want to do is prevent the
pollution from being generated in the first place. But that could only be achieved by switching
of the computer. What we can do is to use as little computational
power possible. The driver electronics for the LCD screen
in a laptop generates quite a lot of noise and therefore a laptop is the worst choice
if you want to connect your DAC directly to a computer. Don’t get me wrong, it will work and might
even sound better than your cd-player, but it is far from being the best that can be
achieved. So a desktop is the better choice but then
you need a passively cooled computer since it sits near your stereo. These are slightly more expensive and although
less polluted than a laptop, they still generate noise and offer poor clock signals. A desktop computer using a special audiophile
USB output and a low noise power supply is a lot better. These are relatively expensive but are your
best bet if you want to use software that only is able to drive the SPDIF or USB output
of a computer. You could use USB reclockers and cleaners
to further improve the quality. There is another way, though, a better way
as far as I am concerned. A computer based streaming system has three
main functions: ripping, database and audio transport. A fourth function could be sample rate conversion
and a fifth other DSP functions like equalising or room correction. The ripping only happens once and need not
be done on the same computer you use for playback. As long as you use proper ripping software,
like dbPoweramp, iTunes on the Mac, Exact Audio Copy or XLD and use proper hardware,
you’re fine. The latter two even generate you a ripping
report so you can be sure it’s a good rip. It is the other two main functions that have
their own demands. Depending on the player or server software
you use, the database function might need some power and due to the nature of database
quarries it will aks for short instances of power making the power supply work hard to
keep the voltage as constant as it can. Not really a good environment for audio. Getting the audio bits from the hard disk
to the DAC is a very easy job as such. It’s like riding a bike – I’m Dutch remember
– a piece of cake when you have mastered it. But still, riding a bike in the pouring rain
with a headwind at close to freezing temperatures is tough. The same goes for transporting audio bits
from the hard disk to a DAC when the power supply fluctuates and all kinds of clocks
interfere with the clock used for audio output. So what you really want is a fast computer
for the ‘administration’ and a easy going computer for the audio transport. Well, that’s possible and doesn’t need
to be expensive either. It is relatively easy to split up the database
function and the audio transport by using two computers – I consider any streamer or
renderer to be a computer too – connected over the network. That has the added advantage of the network
connection usually being galvanically separated by transformers and if not, you could easily
add one. You can do that with USB too, but somehow
that doesn’t give the same result. The second computer can be a Raspberry Pi
with appropriate software and DAC, a streamer like those by SOtM and Sonore plus a DAC,
a networked DAC, a Squeezebox, a DLNA renderer or Roon endpoint in any form or shape from
brands like Aurender, Bluesound, Cambridge Audio, Elac, Denon Heos, Linn, Lumin, Naim,
Sonos, Yamaha and so on. As the server you use a normal computer that
you place somewhere in your house where it isn’t heard so a passively cooled computer
isn’t needed. You might consider using a recent model with
as little power consumption as possible for it will run either all day or is in standby
waiting for a wake up call over the network. Switching it off completely is another possibility
but then you need to switch it on any time you want to listen to music. The alternative might be a silent computer
in the living or listening room so it might be easier to switch it on and off. In this case you need to take care that the
switching mode power supply the computer uses doesn’t pollute the power line and the server
since they are now very close to the audio equipment and audio cables. A linear power supply is the best option here,
although there also are audiofile grade switching mode power supplies. I use a power line filter for all equipment
that uses a switching mode power supply and is close to the stereo, like the PlayStation
3, the plasma tv and the Samsung Horizon DVR. And audio equipment that uses a switching
mode power supply that can’t be bypassed. The best way of working – at least for me
– is to have the server away from the stereo. Wo, back to the question: which server sounds
the best? I use Roon and Roon prefers to be on line
all the time. So I use an Intel NUC computer that has low
power consumption. I have two of them, a 6th gen i3 and a 7th
gen i7. I have also tested with a Mac mini, an old
MacBook Pro and a 2016 iMac 5k. I also tested the Roon Nucleus+ and Small
Green computer SonicTransporter i5. And I really didn’t hear any difference
between them over my SOtM sMS-200 Ultra. As said, when you want to place the server
near your stereo, things get different and depending on the computer the sound will degrade
to some degree. How much depends on the factors I mention
above. Over the coming weeks I will answer more of
these questions. They have been posted many times and need
answering. So if you’re interested in even more of
these, subscribe to this channel or follow me on Twitter, Facebook or Google+. If you liked this video, please consider supporting
the channel through Patreon or Paypal. Any financial support is much appreciated. The links are in the comments. Help me to help even more people enjoy music
at home by telling your friends on the web about this channel. I am Hans Beekhuyzen, thank you for watching
and see you in the next show or on theHBproject.com. And whatever you do, enjoy the music.


  • Ryan Yuen

    Thanks HB for your efforts in running the channel; one question how do you compare the SQ on running Roon server on your intel nuc between "direct USB to dac" and "using a streamer like sMS-200 through the lan network".

  • Mark Nash

    Great summary of the issues with digital fidelity in computer based music servers! As an RF engineer, I believe that shielding issues and ground corruption are 99% of the differences heard in all cables. I have never seen a good case presented with measurements for dispersion being an influence at audio frequencies. I would be interested if you can provide a reference.
    As you emphasized, separation and excellent shielding are the preferred solutions, followed by re-clocking, and then filtering if necessary. There is more value to be added via isolation transformers than I hear discussed anywhere. Perhaps you might address this relatively low cost system component and its applications in a future post.

    Can you elaborate on the limitations of optical SPDIF in the next video? It would seem a preferred noise immune method for streaming to a DAC, located separately at the amp, from the server. My bandwidth requirement for streaming a typical single Audio/Video program in 24/96 at 30fps in 1080p are at about 4MBps. Do typical LAN based systems need to provide 1Gbps speeds at all nodes to work seamlessly?
    Thanks for another great post!

  • Thankful Today

    This is quite a prescient presentation, you always seem to address the right question at the right time. Thank you.
    Have you considered reviewing the Nativ Vita Streamer, DCS Network Bridge, NAD M50.2 or any of the Innuos products?

  • André Vieira

    What do you mean with "near your stereo"? 70cm is near? I wonder how a mac mini could degradate the sound of a stereo just sitting "near" it.

  • Tim Wilson

    Thank you for another great video Hans, I am curious as to what you think about different network connection methods. I have my NUC connected directly to my Wifi Router via ethernet cable. However the house I am renting is not wired with ethernet so I am using Wifi to stream content to my sMS-200. Specifically I am using an IOGEAR Ethernet-2-WiFi adapter powered by an iFi iPower to connect the sMS-200. Alternatively I could use a powerline adapter for a directly wired connection but they are not any faster and I'm afraid they would pollute the power system. Do you think the wifi to ethernet adapter I am using is degrading sound quality? And what are your thoughts on wifi streaming vs ethernet streaming?

  • Selwyn Tan

    Hans, great video! Can I ask if you have tried a linear power supply for your Intel NUC Roon Core? And if it makes any difference if it’s away from your stereo?

  • David Snyder

    Another great topic and presentation. I wish I could click thumbs-up more than once for this one in particular. Well done!

  • amir hajimohammad

    Would really appreciate your thoughts on the Innuos Zen Mini Mk2 as a roon server connected directly to a mytek liberty compared to the options in your video.

  • Nick Carrozza

    Hans, a friend and I were discussing audio over HDMI. He plays music from a harddrive connected to his Mac Mini and runs an HDMI cable directly to his Arcam 550 avr and says there is no down side. Why is this not popular? Is it a quality reproduction of music? Thanks so much.

  • tean tan

    If one is using just a Squeeze box software, eg Daphile in the server, this s/w package is rather small and you do not really need a powerful CPU to drive it, a Celeron or even an i3 cpu is an over kill. Get a cheap fanless server is sufficient. The output USB from the server to a XMOS box a proven by many users(not by me yet) is Singxer F1(there are many nameless Chinese XMOS adapter will cost even less see Ebay) costs about US$170. The Server, XMOS adapter and DAC box will give you VERY good sound. A Chinese DAC based on ES9038 chipset such as SMSL SU-8 or Topping D50 will set you back about US$250. This a very cheap way to get good sound, if you want even better sound then you have to pay more money for well known brands.
    If you are running many packages plus say ROON then a powerful CPU may be required.

  • Affilyon 1

    You have mentioned in video that you always use a power line filter for all equipment that uses a switching mode PS is close to the stereo. I would like to ask what kind of power line filters do you use?

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