Media Player Q&A: Q5 Is there a best method of connecting to a DAC? USB, Toslink, Coax?

5. Is there a DAC connectivity method (asynchronous USB, Toslink, Coax...) that you feel offers superior performance or that makes your product development job more or less difficult?

Jonathan Reichbach, President, Sonic Studio (Amarra)

We still feel that a Firewire or other dedicated interface provides advantages over USB interface. One clear advantage of Firewire (or any dedicated hardware interface) is number of connected devices and how they operate. Consider one Firewire based DAC on a bus as opposed to a USB port with many devices like keyboard, mice and more. Efficient allocation of USB ports can mitigate this problem. USB and Firewire are recommended above Toslink with its excessive jitter.
Damien Plisson, Founder, Audirvana, (Audirvana Plus)
The application can control all DACs as it uses the OS X drivers. Now not all DACs are equal in their interface. There are the so called "Integer Mode capable" ones and the others. That is the ones that can get the audio signal optimized at the kernel CoreAudio level. And this makes a difference.

All DACs that are compliant with the USB Audio Class standard (the ones not needing a specific driver) can benefit from Integer Mode.

Unfortunately most manufacturers that still make DACs with drivers are not sensitive to this important way of improving the sound quality. This may be due also to the fact that Integer Mode was dropped by Apple in Lion from the interface they offer to application developers (the CoreAudio HAL).

But I've found a way to bring it back in Lion and Mountain Lion by bypassing this CoreAudio HAL. This is called Direct Mode, and it is currently in public beta.

Toslink & Coax interfaces need a USB(or FW) to Toslink/Coax bridge to get best results as the built in toslink output of the macs is prone to jitter and limited to 24/96.

Tim Murison, Co-Founder & CTO, BitPerfect Sound Inc., (BitPerfect)
CoreAudio isolates us from most of the details of the connectivity method. For my listening setups, I prefer USB or Firewire connections. Toslink/Coax connections need to use the built-in DAC on Macs, this limits the connection to 96kHZ (on most machines).
Stephen F. Booth, Founder and Developer, sbooth.org, (Decibel)
Decibel uses Apple's Core Audio drivers for communication with the audio hardware, so much of the nitty-gritty protocol transmission details are handled at a lower level than the application itself. In this regard Decibel is somewhat connectivity-agnostic.
Jussi Laako, Owner, Signalyst, (HQ Player)
Not really, different implementations make bigger difference than just the type of connection.
Josef Piri & Marcin Ostapowicz, JPlay (JPlay)
We think that Coax input fed by a high-quality USB->S/PDIF converter sounds best in most cases. High-quality USB & Coax cable are recommended too as they have far greater impact on sound quality than many people would be prepared to believe.
Jim Hillegass, Founder and CEO, JRiver (JRiver Media Center)
Our job is to support the manufacturer in whatever they decide to do. Access to loaner equipment can make a big difference. When we have the equipment, we can always do a great job.
Dr. Rob Robinson, Director of Engineering, Channel D, (Pure Music)
You are asking two different questions. (So there are really 11 questions, eh?) First part, unless one qualifies the answer, the answer is no, except that Toslink has significant limitations and would be my last choice (but it depends if you have an alternative connection method available that also supports up to 96 kHz on your DAC). In the old days, Firewire won out over USB but today’s faster computers render the performance difference minimal (though Firewire is still a better choice for hard drive interfacing because it is much faster then USB 2). Of course, if we are talking wireless connectivity, I think that has to defer to a wired connection in terms of performance (currently can’t do higher than 96 kHz, or play DSD). Second part, no. The connectivity doesn’t matter from a product development perspective, as far as I’m concerned.

COMMENTS
RBremer's picture

I've build a dedicated music server on a PC/Windows 7 platform and use a S/PDIF - coax output directly form the S/PDIF header at the motherboard (Intel® Desktop Board DN2800MT).

We use SSD's for OS and Media Storage, all connected via SATA.

We also use the Fidelizer utility to optimize Windows for music streaming.

With help from friends we compared SQ using various setups with USB-DAC and S/PDIF-DAC  connections (Audio Research DAC8) and our evaluation was that the S/PDIF-DAC way provided better sound  with better stage image and transparency.

This was our evaluation with all possible combinations we tested using the JRiver MC17 output modes (ASIO, Direct Sound, Kernel Streaming, WASAPI and WASAPI Event-Style)

 

I would like to know if someone has tested USB-S/PDIF-DAC connection against this kind of direct S/DIF-DAC connection.

earwaxxer's picture

What about Ethernet vs. USB vs. Firewire etc.