Or if after using a Symphony I/O Mkll in a two-unit setup, you want to just use a single unit - its channel labels may be wrong in Control 2
Scenario
When two Symphony I/O MkII’s are daisy chained together, the Symphony I/O MkII that is connected directly to your MAC is designated as “UNIT A” and the 2nd Symphony I/O MkII that is daisy chained to the first unit will be designated as “UNIT B”.
In Control 2 you can choose which unit you want to view by using the drop down menu in the System Settings sidebar.
Channel Views
When you are looking at UNIT A, the input and output channels are labeled 1 - X.(The number of inputs and outputs you see depends on which I/O modules are installed)
UNIT A
When you are looking at UNIT B, the input and output channel labels start where UNIT A's inputs and outputs left off. In this case 37.
UNIT B
The issue
However, if you switch the order of the Thunderbolt connections, where UNIT A becomes UNIT B and UNIT B becomes UNIT A, the channel labels in Control 2 won’t change to reflect the new Thunderbolt daisy chain ordering.
Nothing bad happens except that if you go to your DAW and want to set it to input 1, you may actually need to set it to input 37. This can be very confusing.
Additionally, if you have your two Symphony I/O MkII’s daisy chained and then decide you just want to use UNIT B alone, the channel numbers that were assigned while daisy chained will remain the same.
Physical input 8 may be seen as input 44 by Control 2 for example.
What is described above is just an example, you may see different behavior.
The Fix
Turn the Symphony I/O MkII’s OFF.
Unplug the Thunderbolt cables.
In your Macintosh HD, go to /Library/Application Support/Apogee/Settings
There you will see 1 or 2 files that begin with “SIO2T-” followed by a string of numbers and letters, and ending in .xml - DELETE these files (you will be asked for your password) and empty your trash. This is 100% safe.
Restart your computer.
Turn your Symphony I/O MkII’s ON.
Re-connect your Thunderbolt cables in the right order: The Thunderbolt cable that connects to the Mac will be your UNIT A. Then use another Thunderbolt cable to connect UNIT A to UNIT B. It does not matter which ports you use.
The channels will now be correctly recognized by Control 2 and your DAW.
What are these files?
They are configuration files that are continuously updated while you are using your Symphony I/O MkII. They keep track of all of the current settings in your Symphony I/O MkII so that when you power cycle it, or if you lose power, it remembers its settings. The issue in this case is that you don’t want it to save its channel labels.