It is possible even, to make Audacity a part of some processing chain. The only problem, that you get, is synchronisation. Some example:
1. First of all - you need to enable devices toolbar, to switch recording and playback source. Not, however, when you finished work, you should switch them back to what you have always (most possible - "System", which is default in most cases), otherwise you will need to get the same ports again before to start Audacity again, otherwise it will fail to start.
2. Run jack-rack. Select it in Audacity both for input and output. Load some track.
3. Try to record something (i think, you already should understand, what is expected, right?). You should get new track with data from first track, processed by JR.
More real example. When i tried to add one MP3 file to audacity by dragging, sometimes it was loaded incorrectly - some parts was lost or modified in strange (for me) way. Solution, i found, is to record it from audacious.