The ALLDAC USB 3.0 ISOLATOR
Tip #91
Dick Olsher (November 2021)

For the past two years I’ve been streaming Qobuz music files off my HP laptop via a USB connection. The target DACs were all excellent R-2R designs, and in particular, the Denafrips Terminator also featured a proprietary USB decoder, that based on my listening tests, is clearly superior to the industry standard XMOS solution. Even in this case, I wasn’t entirely happy with the resultant sound quality. I’m exceptionally finicky about textural purity, and I wasn’t quite attaining harmonic nirvana with my computer audio setup.

It seemed logical to point an accusatory finger at the laptop’s USB output, not really surprising since computer USB outputs are notoriously noisy. The digital signal, 0 and 1 bits, are transmitted by changing a voltage state from high to low and therefore the data can also be impacted by noise.

I started to investigate two devices, the UpTone Audio ISO REGEN and the ALLDAC USB 3.0 Isolator, a German design. Both devices isolate the target device from the computer and regenerate a clean signal. The ISO REGEN was good but not nearly as good as the ALLDAC Isolator which did a spectacular job of cleaning up the signal. It was the clear winner, and since the ISO GEN is no longer in production, this leaves the ALLDAC ISOLATOR USB 3.0 as my top recommendation.

It is available for sale in the USA off the Saelig Electronics website: http://www.saelig.com/product/adq-usb-iso-w.htm.
ALLDAC’s European website is at: https://shop.alldaq.com/Interfaces/USB-3-0-Isolators/ALLDAQ-ADQ-USB-3-0-ISO-PS-3-0-Isolator-incl-Power-Supply::143382.html.

Note that the plug for the external power supply is a two-prong European type and will require a plug adapter.