Currently I have the MIDI sport 2x2 (2 MIDI in, 2 MIDI out) device, but I want to replace it with a Audio/MIDI interface with only 1 MIDI in and out connector.

However, I have 4 keyboards (one sound-less master keyboard, one main synth, and two optional synth I am not sure I will use them; maybe when I run out of sounds of the main synth). The input all comes from the master keyboard (meaning I will play everything from that one, or from the main synth).

The master keyboard is connected to the synth via USB (with MIDI over usb). I was wonder if I get (MIDI) latency problems, when I connect the main synth to the audio interface, and the other 2 keyboards by thru/in one by one from the main keyboard.

So schematic:

- Audio interface, MIDI In/Out to:
- Main keyboard, USB to:
   - Master Keyboard
- Main keyboard, MIDI thru to:
  - Keyboard 2, MIDI thru to:
    - Keyboard 3

1 Answer 1


Every USB-MIDI connection adds at least one or two milliseconds of latency. A single USB connection typcially is not noticeable.

Every DIN-MIDI connection also adds latency; at 31250 baud, a three-byte message requires about one millisecond to be transmitted.

A MIDI Through connection does not add latency, but the MIDI input circuitry slightly distorts the signal (depending of the rating of the optocoupler used in this circuit, which you typically don't know). This can result in problems if there are too many steps in the chain.

  • 1
    Some nitpicking: the distortion of the digital signal adds some latency, because the signal reaches the trigger level later. This effect is increased by each device in the chain. But this should be in sub-bit time. And each MIDI cable adds roughly 6ns per meter, which is not noticable. Mar 31, 2020 at 19:25
  • Thanks and sorry for the late acceptance. Completely missed this answer after only upvoting. Apr 26, 2020 at 20:07

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