The How and Why of Computer Audio.

As I mentioned at a previous post Computer Audio, worth or not?, you can indeed use your PC or laptop for critical music listening with great results. But this can not be done by simply plugging your computer audio out to your Hi-Fi, there are a few things you need to do first.

The good thing about computer audio is that with only a little money you can have a source so good, that otherwise you would need thousands of Euros to buy. Plus it is very convenient to use, since you can control this source from your smartphone or tablet with an app.

I believe that here is one of the reasons why die-hard audiophiles resist to the idea to try computer audio. They feel that it looks so cheap and convenient that it can’t be real Hi-Fi. Or they feel bad since they paid top dollar for a serious looking, heavy CD player that is outperformed by a crappy plastic USB audio interface. Maybe they listened to a poorly configured computer audio system so they have bad experience. Also, there is fear: fear to try something new, fear of learning how to configure a computer, fear that a slow evolving and secure hobby like Hi-Fi will be infected by the computer word, a word where top machines get obsolete at a few months. I was also guilty of prejudice against computer audio, but truth is that when you realize how good computer audio can sound, there is no return.

Does this mean that we should throw away our CD player or our turntable? Absolutely not! I enjoy using and listening to each one of them. I have good CD recordings, good vinyl recordings and good audio file recordings. I have bad recordings in all the formats also. As I have mentioned at my other post Reference Recordings (in terms of quality) I am not dogmatic about the media.

There are some times I just want to listen to the music right now, so I don’t want to turn on my laptop, turn on my USB audio interface, plug in my HDD etc. I just want to turn on my CD and DAC, throw a CD at the player and just press the play button at the remote. After all, you can only appreciate the fact that your CD player will not require an update after you have just opened your best wine, turned off the lights and have a pretty woman near you with the tendency to get undressed under the sound of music.

However, if I had to start with only one source for my new Hi-Fi, (performance wise) my choice would be computer audio. It gives the best sound for less money, it can reach sky high performance and it is very convenient to set up, match and use.

Let’s see the how and why of computer audio.

The computer hardware.


A laptop can look better than a bulky PC at your Hi-Fi rack.

A nice thing about computer audio is that you don’t need a killer machine. A decent Core 2 Duo / 4GB RAM / USB 2.0 / Win7 machine for example will do the job just fine. Apart from that, it is a matter of style. A nice laptop will look better at your Hi-Fi rack than a bulky desktop. More about the role of the PC at sound quality at this post.

The audio files.



Lossless Vs. lossy audio compression.

In order to get good sound, you need good audio files. Forget about lossy compressed MP3 files and stick to good lossless types like FLAC. In a few words, a lossless compression is a compression that reduces the size of the data without reducing the available Information.

The USB audio interface (USB DAC) and the USB Vs. S/PDIF digital connection.

One thing you need to do in order to get high audio performance from your computer is to get a good USB audio interface or USB DAC. The first secret of good computer audio is here: stick to pure computer USB connection. Don’t convert USB to S/PDIF.
There are DACs out there that have both kind of inputs, USB and S/PDIF (digital coaxial or optical). However, almost all of them include a compromise:

• Some of them were designed for USB usage and then they were added with an internal S/PDIF to USB convertor, so they could also be used also as S/PDIF DACs – let’s call them “USB design based DACs”.
• Others were designed as S/PDIF DACs and were added with an Internal USB to S/PDIF converter, so they could be also used as USB DACs – let’s call them “S/PDIF design based DACs”.

For top computer audio performance, stick with a true asynchronous USB based DAC. This is the reason why if you read a DAC review between the lines, you will note that the reviewer favors one of the two kinds of inputs, either the USB or the S/PDIF.

So, if you already have a good S/PDIF DAC for your CD and you are happy with it, leave it alone and just add a new USB DAC or USB audio interface. This is what I did. I use my USB DAC only for computer audio (even though it also has S/PDIF inputs) and I use my Parasound D/AC-1000 only for CD reproduction.

Once again, I am not claiming that one type of connection is “better” than another. I am claiming that if you want a good computer based audio system, since computers are based on USB, use a pure USB DAC and avoid converting USB to S/PDIF.

Synchronous Vs. Asynchronous USB DAC.

If you have already looked for a USB DAC you have probably come up to the terms synchronous or adaptive and asynchronous USB DAC. Actually these terms refer to the way that the data stream is delivered to the DAC.

• Synchronous or adaptive USB DAC is a DAC that is a slave to the computer. The computer decides when to send the data to the DAC and then the DAC has just to convert the digital data to music. Any jitter that might occur here is the fault of the computer.
• Asynchronous USB DAC is the master regarding when to get the data from the PC. The DAC pumps the data from the computer the moment it decides to do so and converts them to music based on the DAC's internal clock. Any jitter that might occur here is the fault of the DAC.

As usual, there is some debate going on here regarding synchronous Vs. asynchronous USB DAC and which sounds better. I am not willing to add a new debate; my humble opinion is to trust the device that was solely designed for accurate music reproduction (that is the DAC) and allow it to have the last word about it. I vote for asynchronous USB connection. Of course I understand that if you choose a USB DAC with a crappy master clock, asynchronous connection is no good.

Software player and the bit perfect output.

It is crucial to realize that for good computer audio you absolutely need the right software audio media player, configured in the right way at your computer. No matter how good your USB DAC may be, if you don’t feed it with a clean digital stream you will get medium quality sound.

Here comes the term bit perfect output. A bit perfect output is a digital stream that carries only the music data that are reproduced by the media player and this stream is not affected in any way by your computer, operating system or media player. It comes out from your USB nice and clean.

An easy way to understand if you have bit perfect output is to trigger a system sound (like when plugging or unplugging a USB stick) while you play music through your USB DAC. If you have set up your computer correctly, the system sound will be reproduced only through the computer speakers and you will not hear it from your main Hi-Fi speakers. This happens because your media player is sending to your USB solely the pure music data stream that nothing else messes with it.

The most famous computer audio media players for Hi-Fi use and bit perfect output are Foobar2000 and JRiver. Me and Panos choose to use Foobar2000, so in a future post I will focus on how to set up the Foobar2000 in order to get bit perfect output and play all available Hi-Res files like FLAC, DSD, DSF, DFF, DVD-Audio, iso etc.

Network playback Vs. USB playback Vs. internal HDD playback.

With computer audio, you can play an audio file that is stored at your network (for example at a NAS), an external USB HDD or at the internal hard disk of your computer.

Of course, there is an argument regarding if the place that the audio file is stored affects the sound quality. Logic says that it shouldn’t – but not all things are what they seem at the world of Hi-Fi.

So, me and Panos decided that we should perform a test. The test was done quite a few years ago (so no solid state disks or USB 3.0 HDD for us back then). We plugged the laptop which had a Gigabit Ethernet port to a healthy Gigabit Ethernet network using Cat 5e gigabit certified cables. We copied the same audio file at an external WD 2.5” USB 2.0 HDD, at the NAS (which also had a Gigabit Ethernet and WD 3.5” HDDs) and at the internal HDD of the laptop. After that we started our usual blind test: one of us was changing on the fly the file that Foobar2000 was playing, the other was listening without knowing what he is listening to.

The results for both of us, 3 out of 3 times was that when the file was played from the USB HDD Vs. through the network from the NAS, USB was sounding superior. By superior I mean that the sound had a bigger and more real like soundstage. However, we could not distinguish the sound quality between the USB HDD and the laptop’s internal HDD.

We found the result awkward and we could not explain why. But we have repeatedly read the same thing at various reviews of network players. Up to this day, for critical listening we keep the audio files at a HDD that is attached through USB connection to the laptop.

Also, we made a test to determine if the HDD affects the sound quality, you can find the post here.

My humble suggestion for a USB audio interface.
As you probably already know, I have chosen the EMU 0404 USB to be my USB DAC. This choice was made with the influence of a tech guru I know and trust. The EMU indeed sounds wonderful as it is out of the box (it has an AKM AK4396 DAC inside) but things get serious with a little bit of tweaking.



My E-MU is hidden deep back in the Hi-Fi rack. I prefer listening to it than looking at it.

Speaking of Hi-Fi tweaking, in the past I was not very fond of it. However, things changed for a reason: I had the privilege to make A/B blind test comparisons between normal and tweaked machines at Panos home (meaning away from third person’s influence) so yes, if the man who makes the mods knows what he is doing, you will get top audio quality.

So, what mods can you make at the EMU? The easy part is to replace the jacks out with RCA out and cancel the volume control potentiometer. The hard part is to replace the appropriate capacitors, make a proper power supply (this proved to be harder than I thought except if you are willing to make a battery PSU) and bypass some of the filtering that stands between the DAC chip and the audio out. After that, you will believe in heaven. Soundstage becomes wider, deeper and everything sounds more focused.

Yes, I know. It is hard to believe that this little USB audio interface can sound so good. You are already questioning my Hi-Fi knowledge. Sorry stubborn audiophiles, been there, done that. As I told you, there is no return. I, me, still can’t look at this ugly EMU with the appropriate respect. After all, heavy thick brushed aluminum faceplates do sound better, right?

Other related posts:

- Can HDDs affect the sound quality in computer audio?
- Is there such a thing as an audiophile PC for computer audio?
- CD Vs. computer audio, CD quality Vs. Hi-Res.

Happy listening as always!

Christos