Hello, this is my first post.
After a long absence from recording I have re-read the manual.
I am using FF 800 with TotalMix FX and have two questions.

1. I have only Playback channels 1+2 and 3+4 active.
I set all others to -infinity in the mixer, chose "Analog+SPDIF" in the bandwidth field of the Fireface settings, selected only 2 WDM devices in the settings as well, and went to Options-->Channel Layout-->Playbacks and hide them.
Still, with the exception of the AN5/6, AN7/8, and AN9/10, all the ADAT playback channels and the SPDIF playback channel show as being "In-Use".

This puzzles me because it only happens with the ADAT PB channels, not the ADAT Inputs or Outputs.

2. I can't quite understand the difference between Snapshots and Layouts. A snapshot stores mixer settings, including channels that show on the mixer. A Layout seems to concern only channels that show on the mixer. It seems to me that a Layout in this way, stores a subset of what can be stored with a snapshot. If this is the case, why have both layouts and snapshots? What am I missing?

Any help greatly appreciated.