Splitter of MIDI signal from one input to four outputs - module for DIY
CHEAPEST MIDI SPLITTER FOR CIRCUIT - YouTube
MeeBlip cubit duo: USB MIDI interface and MIDI thru | meeblip
AmpTone Lab MIDI Splitter - The Midi Store
Amazon.co.jp: CME MIDI Thru5 WC - 1 in 5 out MIDI interface - High speed MIDI Thru for transferring all MIDI data - High precision 1:5 MIDI splitter : Musical Instruments