That looks perfect! Does the code have to change any when doing that? (other than the appropriate MIDI messages)
No, the code is the same. The hardware simply broadcasts the same serial signal to two MIDI OUT connectors.
Also, tried looking that IRLIB9343 up and I can't find it in the usual places. Is it difficult to come across?
It's widely in stock at Digi-Key, Farnell, Newark, etc. But really any P-channel logic-level MOSFET will work fine. The circuit may even work with a PNP transistor too (like a 2N3906) though you can't go out to as many MIDI OUT channels as with a MOSFET. Not a consideration if you only have 2 MIDI OUT's.
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