I discovered a bug in Logic Pro by missing the last movement of a symphony recording: if you unplug your headphones, Logic stops recording. I'm assuming this is because it switches from line out to speakers.
The solution is to route the output of Logic to Soundflower. Launch another audio application (e.g., Amadeus Pro), set its input to Soundflower, the output to headphones or speakers, then launch any operation that allows monitoring the signal. (In Amadeus, open a real-time sonogram window and select Play Through.) Unplugging the headphones now no longer interrupts recording in Logic Pro.
[kirkmc adds: I haven't tested this; I don't use Logic Pro.]
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http://hints.macworld.com/article.php?story=20120303133448613