If PURE DRIVE is connected to your host computer via USB and you want to clock to an external source – i.e. Wordclock Input or ADAT (QUAD only), you must first set the internal clock rate of PURE DRIVE to match the external clock rate and, only then change the clock selection from internal to Wordclock In or ADAT.
Remember, when you are connected via USB, clock source switching must be done from AudioMIDI setup on your Mac, as the RATE and CLK front panel buttons are disabled on PURE DRIVE.
If the internal clock rate of PURE DRIVE does not match the external clock rate when the clock source is changed from internal to external, then it will show up with ‘No Valid Formats’ in Audio MIDI Setup on your Mac. To recover from this state, you must switch back to Internal clock*.
It is also important to note that if you want to change the sample rate of the external clock, you must first set PURE DRIVE back to internal clock, change the external clock rate as desired, then change PURE DRIVE to match the new rate of the external clock, before finally switching PURE DRIVE back to Wordclock In or ADAT.
*There is a known bug whereby PURE DRIVE gets stuck in ‘No Valid Formats’ (no inputs and outputs available) even when switched back to Internal clock. To work around, you will need to unplug/re-plug the USB cable to your computer and/or power cycle the unit to get out of this state. This will be fixed in a future firmware update.