It is not recommended to use FireWire interfaces with multiple Core Audio applications unless you are running Snow Leopard (macOS 10.6).

Prior to Snow Leopard, macOS has a bug that results in audio degradation when a class-compliant FireWire audio device is connected to two or more Core Audio clients at the same time. For example, you could experience drop-outs in Logic Pro if iTunes is also being used in the background.

We recommend that you only connect to a single Core Audio application at a time. Please also ensure that Orpheus/ADA-8 is not your default recording or playback device in order to prevent accidental connection.

Apple have confirmed that this bug is fixed in Snow Leopard.