For the original SGM 2015 music server our primary focus was on reducing DAC filter quality influence by providing a higher quality (up sampled) data stream. Especially DSD DAC’s could greatly benefit from this method and be provided with a means to convert every source format to DSD. Of course the end result would depend on how the DAC processes higher data rates, most DAC’s use different filters for different sampling rates, or they can be user selected, so you would force the DAC to use, or be able to use a different filter this way. Some of the filters and up sampling algorithms provided by HQPlayer which we use for that purpose are so processor intensive you can most definitely not run it on for example a Roon Nucleus, let alone they will run in a DAC’s FPGA. A good example it the Chord Dave which is all about high quality filters and boasts a very strong FPGA array but it cannot approach the filter algorithms quality HQPlayer can provide.Fast forward to this day and age where DAC quality, and DAC filter quality technology has advanced significantly, especially in upper echelon R2R DAC’s, we find ourselves in the situation that the benefit of pre-processing the data has either decreased or is gone altogether. Most of these simply sound best being fed native “bit perfect” data rates. “Low latency” is something computer audiophiles have been hunting since the early Logitech transporter/squeezebox days. We don’t think anybody ever really knew why it sounded better, it’s sought after in the studio recording scene, but obviously to avoid time related sync issues and audio stream interruptions, but not sound quality afaik. There are several tools available to measure a system’s latency to this purpose (referred to as DPC latency, ISR routine execution time, interrupt to process latency etc). It’s generally accepted that lower latency sounds better amongst computer audiophiles though.Lowering latencies reduce active processing times. You can view latency as a roadblock that you cannot pass until its removed. Or shifting your transmission into a gear before you can accelerate. During a latency “wait state”, a processor, memory module or system bus data path is getting ready to accept data packets. It will be active though, drawing current, transmitting its unavoidable EMI and or RFI spectrum which any electrical component will do. With lower latencies we reduce overall system current draw, EMI, RFI and processing durations. Contrary to what you would expect, you can have lower current draw variations and net overall lower EMI / RFI emissions from higher processing power solutions being minimally loaded then from low processing power solutions being higher loaded. The general view that lower power servers generate less noise then higher power servers BECAUSE they consume less current is wrong in our experience. Of course there are a lot of variables in this equation as it’s easier and cheaper to design a low noise power supply for lower current draw requirements so you may very well get better results from a low power solution, especially when using the same power supply. But this is not the design goal of the Extreme.

Now if we can agree on the hypothesis that introducing any type of component into your system can alter your system sound, not restricted to the signal it puts out, it will become a lot easier to explain more differences. No matter if it’s a server, a cd transport, an amplifier, a cable, a fuse, a grounding or ground modulating device. In fact why don’t we extend the definition of your system to your phone charger, your imac, your WIFI router or your new refrigerator?

The attached picture shows how incredible ethernet error correction works. It’s been designed to deal with distortion and noise associated with up to 100 meters of unshielded copper cable. (For general interest, shielding mainly affects NEXT). There’s also additional error detection / handling on a different layer where unrecoverable data is being retransmitted. However incredible all this does significantly increase ethernet PHY power consumption. And arguably we don’t need it’s full capabilities for short connections but it is what it is.

Moving on to Ethernet enabled DAC’s. You will actually have a complete computing environment running an operating system, cpu, memory and a hardware and software networking stack, endpoint software like a upnp renderer, or Roon endpoint software. This is quite a bit more then a USB or AES/EBU receiver. It will most definitely draw more power and have higher EMI/RFI emissions.

But, from a usability point of view, it’s absolutely great as it allows you to stream directly to your DAC from any other networking connected streaming source. However, getting it to sound optimal requires quite a bit of tinkering in your networking environment. The often used selling point it nullifies the influence of your source is definitely not true. And as of yet we are unconvinced it’s the way to go to obtain maximum sound quality.

Your network setup does influence sound, every component connected to it has an effect, even your mobile phone using your wi-fi in a way totally unrelated to streaming introduces activity on all network ports and cables. This includes browsing your favourite Audio Forum. There is a way to reduce this with smart switches/routers, or by using VLANs to segment your network, but this is advanced networking, not typically used in domestic situations.

All network activity causes noise, every data packet travelling your domestic network introduces electrical activity travelling your entire network which is just 1 “subnet”.

This also means your music sever will “see” all data packets travelling your network, it will “investigate” every packet to check if it contains data adressed to it.

A domestic switch will simply replicate all data on it’s input to all it’s outputs, a smart switch provides you with a degree of control over this, so you can segment your network, reducing network traffic on specific links. Again this is advanced networking, none of the “audiophile” switches support this. Now before you think “gotta have”, smart switches apply processing to the data stream, investigate certain parts of all data packets passing through, use more power, and have a noise signature. So there are pluses and minuses to using this in the first place. Network utilisation and the amount of active devices in your network are going to be determining factors if this can net out positive or not.

100Mbit networking uses 2 differential data pairs, 1Gbit networking uses 4. Data is transported as a modulated voltage over these lines. Modulating voltage introduces certain types of noise. In a switch the ports are galvanically decoupled by means of a differential transformer of which the center tap is connected to ground, usually through a simple filter network. One of the functions of this is to break “ground current paths”.

Moving to fiber, we have optical links, SFP modules convert electrical signals to light pulses and vice versa. So arguable there is no real benefit to reducing network activity induced noise, in fact there is additional activity inside your appliances from this conversion process. A SFP module can easily consume 1 to 1.5 watts of power, which does not seem like much, but at this level, it is a lot. On the plus side there is no path for ground currents or electrical noise, whatever the source, travelling your fiber links. There are many types and makes of SFP modules, obvious differences can be found in power consumption efficiency, robustness, error correction, quality of optical receivers/transceivers etc. SFP+ (10G) modules can apply a higher degree of error correction, some even have built in “reclocking or jitter reduction” and yes this draws more power, so positives and negatives. Industrial versions are built to operate in harsh environments, like abnormal temperatures, heavy vibration environments, or in strong RFI/EMI polluted areas. What you can get buying industrial grade is better component quality and tolerance, higher selection grades, more robust PCB mounting and/or layout, better error correction algorithms, better filtering and most of the time lower power consumption. The downside is hefty price tags. We do have a few here.

Your internet router performs quite a bit of processing, it almost always performs something called NAT (Network Address Translation) meaning it forwards traffic from the internet to a different Ip range which you use inside your home. There is both a security and a functional aspect to it as without it each of your devices would require an unique IP address on the whole world wide web, and there is a limit to addresses available, that is why we are for example moving from the IPv4 protocol to IPv6 which has a vastly higher number of IP addresses available. A security aspect is your device cannot directly be accessed from any other device in the world. The router usually also provides DHCP services (assigns an unique address to each device on your local network), can provide DNS caching and often runs firewall software. It also often provides Wi-Fi services. It can be quite a busy device.

By now it must be clear that this is a very complex system with a lot of variables in play. Every network is likely to be unique. Different routers, different switches, different devices using it, different traffic patterns, it is unlikely that there are 2 exact identically performing network setups anywhere in the world at any given time.

Now how does all of this influence playback quality of the Extreme? Well it does, no way around it. So what we have done is running a whole lot of different network setups and combinations to identify the largest disturbances to sound quality. You can take measures to minimize their influence and get repeatable results up to a degree.

The copper network port of the Extreme will provide you with good and repeatable sound quality in virtually all environments. It will sound largely similar in all environments, even in the presence of heavy RFI/EMI pollution.

The fiber network port of the Extreme provides a somewhat different perspective, it will not very significantly impact the overall sound quality or voicing. The plus side is a certain degree of “isolation”. The down side is additional processing and a slightly higher power consumption.
It tends to net out positive with for example blacker backgrounds, improved clarity and more focus without impacting voicing. The downside of the increased focus is “sharper edges” to images, and some SFP modules can introduce a degree of mechanical quality to the sound, the reclocking SFP+ modules being about the worst at that.

So we have recommendations we make, based on repeatable results in different environments, the recommended SFP modules and FMC are based on that. There are combinations which give an impression of higher resolution but it’s important to note increased noise is often perceived as increased resolution. The fatiguing aspect of this usually goes unnoticed as comparative listening sessions are often of short duration with a few test tracks people skip through quickly to remember enough detail to make a meaningful A/B comparison. It is rarely evaluated long term, being over weeks, listening in different moods/mindsets, at different levels of physical or mental fatigue, at different times of the day with varying levels of power grid pollution, or how do you perceive the difference in the first 30 minutes, and then after a few hours of continuous listening. There are again a lot of variations to evaluating.

Therefore our recommendation is to just use copper networking initially, let the Extreme burn in / settle in your environment, so far it has performed to full satisfaction by everybody who has bought one using it this way. Apply basic voicing measures as you would do with any appliance, like powercords, usb cables, footers etc, to adjust it to your taste. Then, if you feel so inclined turn to tweaking your network environment. And don’t take anything for granted there, as your results are not guaranteed to mirror others.

It is relatively risk free to jump straight to using fiber, when used with the components we have tested long term, in various environments, but it is really optional. It is a relatively minor investment with value for money gains though. The downside is it has a “manual”, if you power cycle the server you sometimes have to power cycle the FMC too, or pull the copper network cable from it, so it generates a link fault resetting the interface. But that is really quite a minor issue.

Now keep in mind, network tweaking and audiophile networking products are relatively new, surely there are gains to be made there. But do be aware of all aspects of performance.

There is quite a bit more to AC power then meets the eye. We have voltage and current distortion creating harmonic distortion on power grids. AC power voltage is a sinusoidal waveform which would ideally be a single 60Hz (US) shape. But it is far from ideal, the waveform gets distorted by for example current draw and when it passes through components harmonics are created. 2nd order harmonic would be 2*60Hz =120Hz, 3rd order 180Hz, but it does not stop there, you can easily find up to 50th order harmonics on a powerline, so 3000Hz, and it can go up much much higher then that. All these harmonics are not very useable for our power supplies, but do still “carry power (voltage and current)” and travel our grids. A fuse is basically a resistor, it is quite sensitive to all these harmonics and these will heat it up. It could actually blow just from harmonic distortion while current draw at 60Hz would be well below its rating. Being a resistor it will add its own harmonic distortion. All this distortion is going to be audible. You can create a power supply less sensitive to this, this usually starts at the transformer selection and/or AC line filtering. A fuse would sit in front of all of this though. You could view it as a vibration source, better damped fuses may generate less harmonics, or they may be more resilient to harmonic distortion. And/or these fuses may have a harmonic distortion pattern more favourable to ones hearing and taste.

Everything degrades under stress, powering on a power supply with a large toroidal transformer and capacitor bank produces two significant current peaks, this can easily go over 100A (stress), the toroidal a very steep initial spike, subsequently the capacitor bank draws high current over a longer time period while charging, can be as high as 50A. There are fuses specifically designed to deal with toroidal transformer current surges, those unfortunately have a higher then normal unfavourable effect on sound quality. So it is good practice to soft start this type of power supply to 1) reduce the transformer current peak, 2) reduce the capacitor bank initial charging current, 3) reduce stress on the fuse, 4) reduce stress on the capacitor bank, prolonging life on all these components. Soft starting eliminates the transformer initial surge and cuts the magnitude of capacitor charging current in half in exchange for doubling the charging time. Another side effect is that capacitor charging stress affects sound quality for a considerable time after powering on the supply, soft starting reduces this “warm up” time.

It is these peaks which are the problem why some audiophile fuses can deteriorate early resulting in a lifeless undynamic sound. They can blow after just a few power cycles. If we do not soft start these type of power supplies even very rugged fuses only survive a few power cycles and they audibly deteriorate each power on cycle. We have in fact tested and verified this and it was part of the selection process for this fuse, it will have a healthy long life and can even handle more extreme surges which can happen during power grid anomalies. Obviously we are not going to test all the audiophile fuse variations out there.

It is important to be aware that audiophile fuses can be deliberately overrated (lower resistance, meaning lower heating, lower distortion, which can actually sound better), some are not but blow too fast causing audiophiles to use a larger value, some audiophiles deliberately use larger values as that can sound better, this is actually rather dangerous and can cause significant damage during situations where a normal fuse would blow, it can even cause a real fire as if the fuse not blows while the power supply is delivering more current then what it was designed for, it will keep heating up till it finally fails, or till something reaches ignition temperature. The fuse also protects against power grid anomalies like repetitive voltage swings, brownouts etc, you just don’t know what’s going on when you change the fuse to a different type / rating.

We hold HQ Player, and its creator Jussi, in very high regard. You can get remarkable results from a whole range of relatively affordable DACs by using HQ Player algorithms rivaling much more costly solutions.

We designed the original SGM 2015 Music Server to do precisely that, and extract top-level performance from affordable DACs, using HQ Player algorithms. The value for money equation is beyond dispute.

The current upper market segment DACs do a much better job at “bit perfect” playback than a few years ago. We are following suit with the Extreme Music Server and we now primarily focus on achieving “bit perfect” playback using Taiko-proprietary hardware, -software, and a fully customized USB driver. As a result, we no longer use HQ Player on the Extreme.

But we are in no way suggesting nor implying HQ Player is an invalid approach.