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Positive Feedback ISSUE 41
january/february 2009


Ten Questions about Computer Audio with Larry Moore and Eric Hider of Ultra Fi Audio Designs


Computer Audio has become the new rage in audio and for good reason: one has an easy and instant access to all their music as well the ability to search out countless other titles via the internet.  The issue is simply where to start, though the answer is quite obvious: get a computer, rip and store the files, and then play them back to some DAC. Of course being audiophiles …err the nuts we are… the questions start to pile up rather quickly.

Mac or PC, and then once you got that settled, there is all the minutiae related to just setting-up that computer’s OS and configuration. Then comes how best to rip and how best to save the files, and then to where? Okay, so now that I have my files, how best to play them back and how best to get the files out of the computer and to what DAC? Yadda, yadda, yadda… each question leads to further questions to clarify the previous that then lead to other questions that suggests another question and …a downward spiral down into the rabbit hole we go.

So I went to the 2009 CES and found not only a wealth of information, but a wealth of confusion or at the very least, a wealth of disagreement among those that are either in the recording/software side, the hardware-side, and/or the "expert" sides of computer audio. Now CES is not the best place to get all the answers… time is an issue as is finding all the people to ask, so I came up with 10 ‘key" questions (these are my 10, you may have others or perhaps might not find these of any benefit to you, but I chose them because they are of interest to me and besides they reflect the most common or important areas that seem to pop-up whenever one talks about computer-based audio, so go pound silicon if they don’t work for you.) and emailed them to 12 people in the industry to answer. Their responses are here...


1. Let's start with interfaces; the obvious choices are USB, Firewire, Optical, and S/PDIF. What is your opinion on any of these interfaces? What if any, are the advantages or disadvantages of one over the others in terms of resolution, jitter, etc.?

In terms of interfaces, we are using USB because it allows us to eliminate the S/PDIF interface. In our opinion, S/PDIF interfaces should be thought of as a "very ugly tangled mess". This is because S/PDIF interleaves the sample rate with the digital data. Optical is no different because it is doing the same thing, but just in the light domain. By eliminating the S/PDIF entirely, we completely eliminate its associated jitter. So, USB interfaces are a much "cleaner" approach toward data transfer. Essentially, if you have a higher jitter signal, it destroys many spatial cues and makes the presentation discontinuous i.e. making it less analog like. 

In terms of Firewire interfaces, typically drivers for Firewire connected devices are unavailable for operating systems. Thus a DAC manufacturer would have to write and offer a driver for every operating system. With USB you are able to use the available drivers found within typical operating systems. Our experience has been that every time there is driver update within the computer's operating systems the sonic playback has improved accordingly. A Firewire interface is a constant battle with the drivers comparably.

2. With regards to software there are also strong opinions as to some being vastly superior (or for that matter, inferior) to others; people clearly hear differences in how files are being played back and therefore prefer one over the others. There is also a growing opinion that Pro software is the only way to go and that using iTunes, WMP, MAX, or other free software playback programs (FooBar, JRiver, MAX, etc.) is not the way to go. That is, these are sonically and musically inferior to the Pro software because the Pro software (say for example Amarra, Izotpe, etc.) is simply "better" at playing back music files. What is your opinion on what is going on here? That is, why would any of these programs be superior—or for that matter, inferior—to another with respect to say a .wav file in any resolution: 16/44.1, 24/96, or 24/192? Is it a matter of timing and jitter? Issues with the operating software and processing? The fact that some software runs "cleaner" than others—that there is nothing running in the background to muck things up? Or as some suggest that the "math" is simply better in some software than in others?

For us, ease of use and excellent sound are paramount. Although we haven't tested every piece of software commercially available, we've been very pleased with iTunes to the point that it makes other software choices moot. iTunes is now considered the de-facto standard by many also. This particular subject is where we let our "ears win the battle" over what "sounded great" and we will let the software gurus speculate endlessly as they argue to why other programs should be used "because they think...."

3. Let's move on to ripping. As with the above, there are proponents that claim only certain software, and optical drives for that matter, can "accurately" rip a CD. That they can clearly hear differences between rips via different means; even though the rips are bit for bit perfect. Any thoughts on what is going on here? Is there an advantage to using specific ripping software or drives over another? Say iTunes, WMP, Max or whatever when compared to say EAC?

When it comes to ripping software, we have been very pleased with iTunes so long as error correction is selected. We are glad that iTunes sounds so amazing and hovers right at "top of the heap" of all the choices sonically. From our position, we are just not able to give any specific reasons why one software would sound so darn different from another. Another arguing point for the software gurus to battle about...

4. File formats. Any reason why a .wav, AIFF, or FLAC file is better than say Apple Lossless? Again people suggest a strong preference for one over the others, so something must be going on here?

As far as sonic differences between AIFF and Apple Lossless we have found a slight sonic improvement in AIFF when playing back 44.1 files at the 44.1 setting. However, if one takes the same 44.1 file and up-samples, much of the difference between Apple Lossless and AIFF is ameliorated. We speculate that the differences in sonics are largely explained by the differences in computational overhead associated with up-sampling.

5. There is also a movement towards Pro DACs. Naturally there are DACs of varying quality and performance, but is there any reason why a PRO DAC would be better than a DAC made by a manufacturer from the audio community? Say ones of comparable quality and build?

Initially, perhaps around ten years ago, Pro DACs were a fallout from the recording industry. Pro DACs were a necessary means of monitoring the recording process. Today, there is no reason why a "high end" audio DAC manufacturer cannot be just as experienced as a Pro DAC company. Additionally, Pro DACs (more often than not) don't meet the same internal circuitry build standards that audiophiles demand. Indeed, it is very rare to see something like a great sounding film capacitor anywhere inside a Pro DAC. The resolution and "magic" of both the active AND passive components are paramount to a competent audiophile DAC manufacturer comparably.

6. Along those same lines, what makes one DAC a better choice for computer-based audio than another? Jitter reduction, chip sets, power supply, etc?

Well, as far the technical "choices" needed for computer based DACs we have found that EVERYTHING still needs to be addressed. The sonic merits of each area can and do apply throughout. Basic power supply regulation, RF interactivity, D/A converter chipset choices and the output stage choice along with the subsequent passive components still all play a large part in the overall capability of the product. However, we've found that careful attention to jitter reduction, particularly in the input receiver so as to supply a low jitter signal to the selected DAC chip goes a long way towards homogenizing the differences between DAC chips—assuming the balance of the circuitry is comparable up as to par. Thus, of all the things needed to make a class leading DAC, if there is "sloppiness" in the designer's choice as to the input receiver alone, the DAC will fall very short of it's true potential. Frankly, any and all products based on the TI/BB PCM2700 series chip are simply not at the cutting edge of today's available technology and do not offer the benefits of a lower jitter clock. Just like in all things in high end audio, the product can only sound as good as the weakest link. Even the designer's choice of adding a S/PDIF interface works to the sonic detriment to the USB connection's sonic greatness.

7. What do you see as being the most important factor in getting the best sound in computer-based audio? That is what should the consumer address with the greatest concern when setting up a computer-based audio system?

In order for the user to make his computer set-up sound it's best one of the most important facets is actually the USB cabling choice. The difference between the sound of USB cabling is pretty darn large when you compare a generic USB cable a great audiophile USB cable. It is even larger than we ourselves were capable of understanding as we entered this journey into high end computer DACs. Other facets for the user to consider is having their hard drive separate from their computer and using a desk top machine as opposed to a laptop. Computer noise, RF interference and other "electrical nasties" seem to the enemy of getting the best sound from a computer based playback system. Whenever you can reduce or eliminate these interactivities (like having a separate hard drive away from the computer and moving the screen away from the processor) there is always a subsequent sonic improvement in our experience.

8. Along with that, what do you see as being the most important factor in NOT getting the best sound in computer-based audio? That is, what can have the greatest potential to adversely affect the sound in computer-based audio?

As stated above, reckless care of using something like a "Best Buy" style USB cable and/or having the music data contained altogether in one computer without considered separation of external hard-drives and the computer's screen from the proximity of the computer processor will "squash" the true sonic capability of the DAC considerably.

9. Some suggest that they computer must be audio dedicated. That is it must be "built" or configured for the specific purpose of only playing music and that any and all non-audio related programs and such must be eliminated. Your feelings on this? Is it important or not, and why so?

Since we have achieved fairly amazing sound from a standard Mac computer solution, we wonder if there would be much improvement (if any) for a fully dedicated, built for one purpose only—"audio computer solution". Of course, it all comes to pragmatics here. Someone could probably build a very unique "Uber expensive" dedicated computer that had everything imaginable done. The true question (in our opinion) is how much sonic improvement is actually achieved with the "Uber computer" as compared to a properly set-up computer with a separated hard drive, separated screen comparably.

10. Where do you see the greatest impact to come in computer-based audio for the future?

Higher resolution music material, downloads and a trend toward better recording care at the studios - where all the magic starts!

Larry Moore is founder and chief designer at Ultra-Fi Audio Designs. He is best known for his Award Winning SET amplifiers which he has been making for 17 years. Larry's foray into digital started many years earlier (in 1984) when he first started modifying digital CD players/DACs from many well known high end digital companies. For many years, Larry was a very “hard-core” analog music lover with an analog rig that had five different tone-arms and cartridges.

From his days at Bell Labs, where he was as a senior RF Engineer, Larry has developed many unique and proprietary discoveries into his many Ultra-Fi products. Prior to those days, Larry worked in the military on secret projects. After Bell Labs, Larry went on to acquire a law degree and work as a patent lawyer. Currently, Larry Moore's focus is to produce the best sounding digital possible—equaling the sound and liquidity of the very finest analog systems.

Eric Hider is Ultra-Fi Audio Designs' Sales and Marketing Manager. He is an Electrical Engineer that has worked in various Aerospace, Microprocessor and the Automotive industries. He has also been a very active "hard core" audiophile himself for over 30 years.

Use the links below to read other responses to these questions

Larry Moore and Eric Hider of Ultra Fi Audio Designs

Andreas Koch of Playback Designs

Tony Lauck

Steve Nugent of Empirical Audio

Gordon Rankin of Wavelength Audio

Jon Reichbach of Sonic Studio/Amarra

Vinnie Rossi of Red Wine Audio

John Stronczer of Bel Canto Designs

Daniel Weiss of Weiss Digital Audio

Vincent Sanders and John Hughes of VRS Audio Solutions

Kent Poon of Design w Sound

Charles Hansen of Ayre Acoustics

Pete Davey of Positive Feedback Online