Is there some reason that Yamaha doesn't support USB MIDI class compliance? On the MODX, neither USB interface is class compliant: the "USB-TO-HOST" terminal can only be connected to a computer running a Yamaha device driver, while the "USB-TO-DEVICE" terminal only supports a USB memory device. Since more and more MIDI products (keyboards, controllers, accessories) don't have the original 5-pin MIDI interface and only have USB MIDI class compliant host or device interfaces, the only way to connect these to the MODX is through costly and inconvenient USB-to-MIDI adapters - or a computer, which a lot of us performing musicians don't want to deal with on gigs...???
df
Yes, it would be nice for the USB-to-Device port to support USB-only devices.
The USB-to-Host port does not require a driver. The driver is required to get all of the enhanced software support - but you can connect the port without loading a driver and you will get class compliant built-in support. This allows for audio and MIDI to work. What you don't get are all of the discrete audio channels. That takes the driver. But you do get some audio I/O channels.
That doesn't do anything for what seems to be what you'd rather have - a way to connect devices to MODX's device port.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R
As the OP only mentions midi and not audio, can I chip in to say that I use the MODX with an android tablet and a very cheap USB OTG adapter. The tablet and MODX work fine together with no drivers or costly usb midi interfaces needed. This is where I got mine from, you then need a typical (A to B) USB cable used for printers:
https://www.kenable.co.uk/en/usb-cables-adapters/usb-20-cables/6631-otg-usb-on-the-go-host-adapter-cable-usb-a-female-to-micro-b-black-006631-5055383466313.html
The way I read this the OP is wanting to interface to a MIDI device (examples would be the Korg nano series such as nanoKey) directly without needing a tablet, computer, or dedicated usb-to-din-midi interface such as the Kenton USB MIDI host.
Although I corrected one error in the original statement, the main wish of the OP (as i understand it) is still pointing out a limitation that cannot be overcome.
Current Yamaha Synthesizers: Montage Classic 7, Motif XF6, S90XS, MO6, EX5R