Some Synthesizer or hardware produce hiss when we being connected to USB especially to the high frequencies (See my article about the Connections & Background Noise).
![USB Hiss](http://keyboardwaves.com/wp-content/uploads/2017/03/Usb-Hiss-744x439.png)
Listen the USB Hum :
I give you a tip to remove USB Hum for under 30$ without any D.I Box : the USB Isolator.
![](http://keyboardwaves.com/wp-content/uploads/2017/03/Nord-Stage-2-USB-Isolator-420x420.jpg)
I bought this HiFimeDIY USB Isolator for my Nord stage 2. I use USB cable to transmit the MIDI to my Macbook but some static appear in the Audio Line Output of NS2 when I plug the USB cable.
So with this USB Isolator, the Nord Stage is isolated from the ground loop caused by this connection and Audio Outputs are totally cleaned.
![](http://keyboardwaves.com/wp-content/uploads/2017/03/Normal-Noise-744x438.png)
Another advice if you use a hub to many MIDI/USB connection between your machines. Connect the USB Isolator after the USB HUB because synthesizers can cause ground loops between them.
![](http://keyboardwaves.com/wp-content/uploads/2017/03/USBHUMOK-420x315.jpg)
![](http://keyboardwaves.com/wp-content/uploads/2017/03/USBHUMNOTVALID-420x315.jpg)
PS : This Tip works with Motif XF if you don’t use D.I with lift ground. But you don’t cut the ground loop, only the USB Hiss.
Hifimediy USB Isolator sold here :
https://hifimediy.com/product/usb-isolator/