Unfortunately there is not support for having the units daisy chained together. Some individuals have gotten the secondary outputs to work on their systems, while others have not. Here is some info on daisy chaining the FireStudio Projects, but no guarantee on if it will help solve your issue.
Please turn off both the units, then disconnect them and do the following:
1. Download and install the latest version of Universal Control for the FireStudio Project:
http://www.presonus.com/products/FireStudio-Project/downloads
a. Locate the installer package for the operating system you are using.
b. The top link is the latest release of the package installer available and includes the driver.
2. Connect the first FireStudio Project by itself via FireWire and then run Universal Control.
a. Open Universal Control and select "Settings"
b. In the drop down select "Check Firmware", update the firmware if available.
c. If the Firwmare is already up to date, close Universal Control, power down your unit and disconnect it from the computer.
3. Connect the second FireStudio Project to the computer, open Universal Control and connect the unit via FireWire, power it on and repeat the process to assure the firmware is up to date with the latest version of Universal Control.
4. Once you have confirmed both units are on the same firmware and they sync by themselves;
a. Connect the FireStudio Project with the lowest serial number to the computers FireWire port and power the unit on.
b. Connect the FireStudio Project with the higher serial number to the second available port on the back of the first FireStudio Project and power it on.
- You should now see both units in the small Universal Control window, each with its own separate mixer set up at the bottom. The lower serial numbered unit should default to the master in the clock source of Universal Control.