When an H9 is connected to a MIDI host with a USB cable, does that H9 both send and receive MIDI commands through that one USB cable?
Yes. But the host should be something like a PC/Mac, but not a MIDI controller.
I ask b/c it appears that the Disaster Area Midi Baby (3) has usb and DIN ports that are assignable for MIDI THRU. So it seems I could achieve the goal described above as follows:
Connect a MIDI Baby to a first H9 with a USB cable. Set the MIDI Baby DIN port as MIDI THRU. And, connect the MIDI Baby to a second H9 using the DIN port.
That way the MIDI Baby could send MIDI commands to both H9's and MIDI commands from the first H9 would still make it to the second H9 (it would be irrelevant that one H9 is communicating through USB and the other is communication through DIN). Is that correct?
No. Because once you connect USB port on your 1st H9, it disables it DIN input and output. Why don't you just connect MIDI BABY to your 1st H9 via DIN, and your 1st H9 to your 2nd H9 via DIN as well? Set your 1st H9's MIDI setting to thru, then you can use your MIDI BABY to control your 2 H9s.