An issue was discovered with the latest release of Universal Control AI (v30286) when recording cacaded StudioLive AI consoles on a Mac. The 4.2.0 firewire driver included in UC-AI v30286 will produce distortion in the recording of cascaded mixers on a Mac.
Software Engineering is currently working on a fix to be released in a future update, but until then the primary workaround would be to use Universal Control AI v28882, as it uses the 4.1.4 firewire driver version which does not exhibit the problem.
See here for instructions on uninstalling Universal Control-AI on Mac: http://support.presonus.com/entries/23020690-How-do-I-Uninstall-Reinstall-my-device-drivers-for-the-StudioLive-AI-on-a-Mac-
Universal Control-AI v28882 can be downloaded here:
http://www.presonus.com/products/StudioLive-AI-Series/downloads
*NOTE: for OSX 10.10 Yosemite users, because of Apple's new kernel security code-signing checks, will not be able to use UC-AI v28882 without performing a workaround to disable these kernel code-signing security features. See here for the workaround.