Direct Monitoring steps when stacking (daisy-chaining) 3 AXR4T units?

Happy owner of an AXR4U, but I’m thinking of upgrading to 3 x AXR4T units, so I can daisy-chain them. I was wondering how to setup direct monitoring for 3 units? The manual on page 51 describes how to direct monitor when 2 units are connected…

  1. Make sure that the computer is off, and
    that the [P/I] (standby/on) switch on the
    AXR4T device is in the standby position
    ([P] position).

  2. Use an ADAT cable to connect the
    OPTICAL A [OUT] connector on the
    second AXR4T (page 7) to the OPTICAL A
    [IN] connector on the first AXR4T.

  3. Turn on (I) all AXR4Ts.

  4. Boot up the computer.

  5. In dspMixFx AXR, set Digital Port A for all
    AXR4Ts to “ADAT” (page 51).

  6. In dspMixFx AXR, set the signal to be
    monitored on the second AXR4T to the
    OPTICAL A connector (page 51).

But I’m wondering how to connect things when using 3 units? Anyone?