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If your set-up will only involve the three Elektron machines and no other gear (which is fine) then you will have a good set-up with the three machines synchronized by MIDI and by sending the main audio outputs of the AF and AR to the audio inputs of the Octatrack. If you read the section ‘Octatrack as a performance hub’ on pages 119 to 121 of the Octatrack manual, you will get a thorough guide to setting up your gear in this way.