What is MIDI Host? What is a MIDI Hub and how do I use it to connect different modules to the ARP? Why is it better than daisy chaining?
The USB Host port can be used to plug USB devices directly into ARP. This is useful if you have a MIDI controller that doesn't have a MIDI DIN Out.
A MIDI Hub can be used to split the sending of MIDI messages to different devices. I.e. One cable out of ARP connected to the hub, then the hub connects to many devices on separate cables.
Something like this: - https://kentonuk.com/product/thru-5/
You can of course use daisy chaining, using MIDI Thru. I.e. A cable out of ARP connected to Device 1 that sends the MIDI data out to Device 2 on the 2nd MIDI cable.
This has two potential drawbacks though. Some devices don't support MIDI Thru and many devices use what's called a "software Thru". In the latter, each MIDI IN message is processed and then resent via the MIDI Out.
MIDI data is serial and each MIDI message takes around 1 millisecond to process. There are a lot of messages to process so this delay can cause an audible lag.
If you have, for example, 5 devices in a daisy chain, the 5th device will take at best 5ms to receive the message. If you have a lot of MIDI messages it can take far longer and that may disrupt your music.
A MIDI Hub forwards the MIDI data, in parallel, to each of its MIDI Out ports. Therefore, each connected device receives the data at the same time.
For a small number of synths, daisy chaining is perfectly fine and you'll probably never notice any lag.
I often use a 1 to 3 Hub and daisy chain 2 or 3 synths on each output.
I hope that helps.