The front USB port can be used to extend the inputs for STRUCTURE. You can connect USB class-compliant MIDI interfaces, MIDI keyboard controllers, numeric keypads, and regular keyboards through this interface. You can use a USB hub on this port, but see the important power considerations below. Without anything attached to the USB port, STRUCTURE will pull ~400ma during the heaviest NODE SET computation operations. This number grows when you insert USB devices into the USB port. With a few MIDI devices, it is not uncommon for that value to rise to ~650mA total current on the +12V rail. If you are worried about power usage in your case, it is recommended you either use a powered hub to offload the power consumption from the USB port or you plug an external +12 supply into the back of STRUCTURE.
External +12V Power Reference
NOTE: If you use too much power from your case power supply, it is possible that STRUCTURE could spontaneously reboot from being current-starved. We’ve tested STRUCTURE in some heavily loaded cases and it has never rebooted on us yet, but be aware if you have a really low power case.