Isolator

There are claims that sound quality improves by having a full galvanic isolation between the PC and the DAC. Some manufacturers of USB DACs use opto-couplers to eliminate the noise from the USB connection.

Exasound provided some measurements demonstrating the difference galvanic isolation can make.

 

Beware that although USB2 is supported most of the time, this doesn’t mean all the USB speed modes are supported as well. A DAC able to play > 24 bit / 96 kHz needs High-Speed (480 Mbps). A lot of isolators in the past were limited to Full Speed.

 

As opto-couplers are used, why not use them to drive a fiber.
This gives you USB over optical hence galvanic isolation and a cable length well in excess of the 5m the USB standard allows for.
This is a technology employed by a couple of extenders.

 

Uptone Audio took matters a bit further. Their Regen is not a isolator (protecting the device against a high voltage) but a re-clocker. It re-generates the USB stream.
Their Regen generated quite a stir at various audio forums.

Likewise the Audioquest Jitterbug.

 

AmirM measured the jitterperformance of the Regen and the Jitterbug.

His conclusion:

Objective Analysis Summary
Simply put, there is no good news here. Both devices degraded the performance of the DAC a bit and did nothing to improve it. There are reasons for this that I won’t go into but let’s be careful in using our intuition that when something is “filtered,” it is always good. That is not how this interface works.

Science Thread: Review of Audioquest Jitterbug and Uptone Regen USB Conditioners

Although the manufacturers of these products wax away about the improvements in audio quality, most of them don’t supply measurements.

 

USB Cleaner

USB Cleaner

 

References