Multiple MAINFRAMEs (5-pin MIDI)
Use multiple MAINFRAME-B+ units by routing with 5-pin MIDI.
With a MIDI Hub
An example of a MIDI Hub:
With a TRS-3.5mm Splitter
An example of a TRS Splitter:
If using a TRS-3.5mm splitter, use a high-quality one and keep the cables as short as possible to prevent data corruption.
Depending on your MIDI hub (and definitely if you use a TRS-3.5mm splitter) the MAINFRAMEs will receive the same MIDI signal. There are a number of interesting effects depending on how you set the MIDI channels on each MAINFRAME. See MIDI Channeling Schemes for more information.