Am having a hard time understanding what in my setup elicits the following behavior:

1) A stereo signal is sent from the 2012 Mac Pro (High Sierra) through the HDSPe AES (at 96kHz), from there to an Aurora 16, where its meter shows a stereo signal (ch 1 and 2) switched to either analog or digital.

2) TotalMix shows a stereo signal on 1/2 out, no matter what is done to HDSPe Settings.

3) At 96kHz on HDSPe Settings and Aurora, the Single or Double Wire setting in HDSPe Settings changes what analog passes the Aurora. When Single Wire is chosen, Aurora's meter shows channel 1 passing the Aurora, and is heard in mono through the monitoring chain. When Double Wire is chosen, a stereo signal passes the Aurora's ch 1 and 2, and shows up in stereo in the monitoring chain.

4) Changing HDSPe Settings and the Aurora to 48kHz alters this behavior: now the stereo signal from the Mac is shown in Totalmix in stereo, is shown as such on the Aurora (switched to Analog or Digital) and is heard in the monitoring chain - regardless of Output Format in HDSPe Settings (Single or Double Wire).

Assuming that this as usual is due to operator error, how can I understand how I have caused this to happen? I am under the impression that audio card (HDSPe) and interface (Aurora  16) are to be set to the same sample rate. The above behaviors are as they are with no sync or with AES sync. Have I understood the manual, that choosing Double wire at 96kHz cuts available channels in half (from 16 to 8)?

Anyone?