Updated July 2, 2021
Set to Wordclock or ADAT Master with the UA Apollo set as a synchronized device.
For those that are not familiar with SMUX. SMUX mode is 24/96 over ADAT lightpipe where half of the normal channel count are available at double the sample rate. The effective channels as denoted on the back of the unit are (1-4) or (5-8) or both (1-4) and (5-8) at the same time using all 4 ADAT Ports for a total of 8 channels of 96kHz.
We found during the course of our testing that most interfaces send the SMUX bit correctly and the channels send correctly.
However a couple of interfaces do not send the SMUX bit correctly which manifests in a way where the channels (1-4) double up across all 8 inputs. So it shows up as (1-4) and (1-4) instead of (1-4) and (5-8).
The devices that do not send the SMUX bit correctly include the Universal Audio Apollo and the Yamaha 01V96.
Other devices that we tested with including the M-Audio ProFire 2626, M-Audio 1814/ / Project Mix, RME FireFace, Focusrite, PreSonus 1818VSL and Avid Pro Tools HDX all worked correctly.
However if you set the DP88 as clock master and set the UA Apollo (or Yamaha mixer) to ADAT or Wordclock synchronized device, then SMUX works correctly.
The UA Apollo (and Yamaha Mixer) can receive SMUX commands but cannot send them.
We have notified product management at Universal Audio about the problem.
Please contact them to see what plans they have to resolve the issue.
Please contact PreSonus Technical Support by creating a Support Ticket at My.PreSonus.com for further assistance.