I am a Moxf6 owner and I am very happy. in my studio is connected via usb cable with a laptop and via midi cable with a master keyboard .
Of course when i connect to pc the second keyboard (master) doesn't work..there is some chance to use the two keyboards + the computer together or one excludes the other?

What you may not know is that YES (of course) you can use your other keyboard along with the MOXF6 while connected to your computer.

The MOXF has a built-in Audio and MIDI Interface. This means that you can use multiple keyboards as input devices to the computer and use multiple devices to receive signal from the computer... this is because the MOXF has both audio and MIDI capability via its USB connection... perfect for setting up one external device to send both MIDI and Audio through the MOXF to the computer.

Here’s how it works:
Download and install the “Yamaha Steinberg USB Driver” appropriate for your computer type and operating system
Set the MOXF6 to MIDI I/O = USB

The USB connection between MOXF and the computer is the equivalent to 10 MIDI cables! That’s right 5 MIDI cables going to (IN) and 5 MIDI cables coming from (OUT). Each In/Out pair is referred to as a “Port”

Port 1 - addresses the 16 Parts of the MOXF Synth engine
Port 2 - address the DAW software as Remote Control Surface (Start/Stop; arm Tracks, open/close windows; etc. there are templates to control Cubase, Logic Pro, Sonar, Digital Performer)
Port 3 - addresses your external MIDI device connected to the 5-pin MIDI jacks on the MOXF back panel.
Port 4 - addresses the “Yamaha MOXF6/MOXF8 Editor Standalone/VST” which allows you to setup the MOXF VST.
Port 5 - address the “Yamaha MOXF6/MOXF8 REMOTE EDITOR” which lets you create custom controller setups for and VSTi soft synths you want to remotely control from your MOXF front panel knobs and buttons.

When the MOXF is set to MIDI I/O = USB the MIDI jacks are disabled for the MOXF but become available for your external Keyboard Controller via PORT 3. Connect the MIDI OUT of your external keyboard to the MIDI IN of the MOXF (acting as the MIDI Interface). It will be passed on to the computer.

That means any Track set to receive data from either of your keyboards can be routed to the DAW... you can play either of them or both at the same time. In a DAW, like Cubase you would simply setup MOXF Port 1 and Port 3 as MIDI INPUT Ports. Then set the MIDI out to either Port 1 if you want to trigger the MOXF... Set the Out to Port 3 if you want to trigger your external Synth.

If, for example, you wanted to play the external set of Keys to trigger MOXF sounds, you would set the MIDI IN of your Track to “Yamaha MOXF6/MOXF8-3” (Port 3), and set the MIDI OUT to “Yamaha MOXFY/MOXF8-1” (Port 1)

If your external device outputs sound, connect the L&R outputs to the A/D Inputs of the MOXF; you can route the audio of your external Synth on its own discreet stereo audio bus to the computer. The A/D Input defaults to USB 1/2... The MOXF defaults to USB 3/4.

The MOXF is far, far more powerful than you might think!
Hope that helps.

many thanks for your answer!
Now it's ok!! Very useful.
Best regards
Gianni