Computer-based audio playback may not have the best audio quality through its USB interface. By default, laptops and desktops use switching-mode power supplies. For laptops, the DC jack uses 19V, but internally DC-DC converters are used to generate 12V, 5V, 3.3V and the lower voltages used by the motherboard. When audiophiles use 19V linear power supply for laptop used to play music connected to hi-fi system, the use of DC-DC converters internally resulted in less-than-desired sound quality when used for audio playback.
This is also true for serious computer-based music servers and streamers. If linear power supply is used through the motherboard’s ATX connector, voltages lower than 3.3V will be generated by the motherboard using DC-DC converter, causing the motherboard’s ground to be noisy.
One way to address this problem is to isolate the noisy ground. A separate 5V DC power supply which does not share the same DC ground with the computer is required. The USB signal is then regenerated / repeated, resulting in cleaner USB signal and better sound quality.
AA USB2 Isolator
Our USB2 High-Speed Isolator is based on Texas Instruments USB2 Isolator chip which provides 5kV isolation. Even if the USB DAC already have USB isolation implemented internally, the use of external USB2 Isolator may improve the sound quality further.
We have tested AA USB2 Isolator with the following DACs:
| DAC | Has USB GND Isolation? | Any SQ Improvement? |
|---|---|---|
| Holo May KTE | Yes | Yes |
| Denafrips Terminator Plus | Unknown | Yes |
| Chord Hugo TT2 with MScaler | Unknown | Yes |
| Chord Dave with MScaler | Unknown | Yes |
| Marantz SA-10 USB B DAC Input | Yes | Yes |
| Matrix Audio xSabre | Unknown | Yes |
| MSB Reference | Yes (ProUSB Input) | No |
We have also tested AA USB2 Isolator with the following digital sources:
| Digital Music Source | Any SQ Improvement? |
|---|---|
| Windows laptop | Yes |
| iMac | Yes |
| Intel NUC | Yes |
| Roon Nucleus | Yes |
| Sony HAP-Z1ES | Yes |
| Innuos Zenith Mk2 | Yes |
| Lumin U1/U2 Mini | Yes |
| HiFi Rose RS250 | No |
The combination of digital source and USB DAC used will determine the final outcome whether AA USB2 Isolator is capable of improving the sound quality.
The USB2 High-Speed Isolator is now ready for order. These are the pictures of the latest version which can be used internally inside AA Music Server or used externally with any other music servers / streamers or laptops.
The size is relatively small, even though it looks big in the pictures.
The introductory price is RM1,200 without 5V DC LPSU. We plan to offer our own 5V 1.5A low-noise LPSU very soon.
AA USB2 Isolator is available for demo at Stars Picker Audio Library, Kota Damansara, PJ.