As you can see this Plugable USB2-HUB7BC is working well on my Montage. Read my LED screen which is running off the Plugable USB adapter and showing all the flash devices available. I’m also powering/charging my LED from this hub. No more annoying process of blindly reaching behind the Montage to remove the flash drive and plug-in the adapter over and over again.

https://www.amazon.com/Plugable-Charging-Adapter-Support-Android/dp/B00L2LK164/ref=sr_1_1?ie=UTF8&qid=1466122889&sr=8-1&keywords=USB2-HUB7BC

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Information From Yamaha.

Page 54 of the Owner’s Manual

Precautions when using the [USB TO DEVICE] terminal
This instrument features a built-in [USB TO DEVICE] terminal. When connecting a USB device to the terminal, be sure to handle the USB device with care. Follow the important precautions below.

NOTE
For more information about the handling of USB devices, refer to the owner’s manual of the USB device.
Compatible USB devices
• USB flash drive
Other USB devices such as a USB hub, computer keyboard or mouse cannot be used.
The instrument does not necessarily support all commercially available USB devices. Yamaha cannot guarantee operation of USB devices that you purchase. Before purchasing a USB device for use with this instrument, please visit the following web page: http://download.yamaha.com/
Although USB devices 1.1 to 3.0 can be used on this instrument, the amount of time for saving to or loading from the USB device may differ depending on the type of data or the status of the instrument.

NOTE
The rating of the USB TO DEVICE terminal is a maximum of 5V/ 500mA. Do not connect USB devices having a rating above this, since this can cause damage to the instrument itself.