Native Instruments B4 II - Manual (Page 28)

28 – B4 II B4 II
MIDI
If your MIDI interface offers multiple ins and outs, you can choose which one
connects to B4 II. When you click on the MIDI tab you’ll see a list of MIDI
I/O. Initially, each one will be Off. This field is a toggle – click on Off to turn
an input or output On, click on On to turn an input or output Off.
If you enable more than one input, they will be merged.