High Speed USB DAC?

A recent article in Stereophile ( July 2011, page 45 ) indicates better sound may be achieved when a USB DAC is on a High Speed USB bus.

I have a PS Audio Digital Link iii. My Mac Mini, using as Music Server, will only recognize the USB Audio Codec ( PS AUDIO DLiii ) on the Non High Speed USB Bus. I've contacted PS Audio and they don't seem to have a clue about this. Anyone know if this device is capable as a High Speed USB device? Am I wasting my time and won't see any realistic sound improvement?

Thanks in advance
I would post your question to Chris Connaker on the Computer Audiophile site that he runs. Either he or one of the many members of that site I am sure will be able to help out. http://www.computeraudiophile.com
Thanks Cmalak - great suggestion. I've been to his site many times.
Related question: anyone know how to change which device is on the high speed bus? Simply swapping sockets and restarting did not do it for me.


The problem is not the computer. The Mac mini has a USB 2.0 USB bus which is considered high speed as most computers do since 2003. The problem is that the DAC may only be using a USB 1.1 USB input receiver and or software or both. The perfect example is with Ayre QB 9. The original QB 9 was limited to 96K once they were able to either change the USB input receiver or upgrade the software and or both they now were able to make their DAC sound much better regardless of digital format i.e. High Resolution or standard CD resolution the difference is immediate with their new improved high speed USB input receiver. High Resolution still sounds better than standard resolution it is that now that they both sound much better because the faster the data flow between the computer to the DAC thus better bandwidth. The newer QB 9 DACs are now capable of higher resolution than 96K with 24 bit words. I think they are now capable of 192K. I have heard both and in A-B comparison and newer QB 9 sounds better, than the original and I do not know for sure but from what heard they only changed the USB input from USB 1.1 to USB 2.0XX
If the change is from USB 1.1 to USB 2.0, then it probably means that the USB interface changed from adaptive to asynchronous. This means that the computer instead of "pushing" data to the device, the device is now "pulling" data from the computer. This establishes a master clock in the device.

Steve N.
Empirical Audio
In the case of the Ayre QB 9 it was asynchronous already with the USB 1.1 input with the USB 2.0 it now allows more bandwidh i.e. 192k to flow. Another good example is the Music Streamers second generation DACS which now have input receivers capable of 2.0 but only have 1.1 USB software. They are asynchronous and are considered USB 1.1 and can play 96K files and is asychronous. The next generation Music Streamer will probably address USB 2.0 and allow for decoding and playing 192K files.
Thanks to all for your responses. PS Audio confirmed that the Digital Link iii will not show up as a High Speed Device. They also confirmed that high definition (24 bit 96/192) capable USB DACs will utilize the High speed bus while the DLiii is only 16/48 USB.