Would it be possible to make an audio seqencer using XNA that works by triggering XACT cues periodically using a timer. Would the timing be precise enough to synchronize several audio clips into one loop? (Think Ableton Live)
Not sure if you'd be able to, but on the bright side, you most likely don't have to.
If you're just trying to create a series of sounds to play in a row (and even loop that series) that can all be done in XACT.
When you have the XACT project open and all of the wavs added and corresponding Sounds for them, just drag the sounds onto the Cue that you want to use. In the bottom-left panel, you can control how the cue uses the selection of sounds.
For instance, Random will just play one of the sounds with certain probability, but it sounds like you want "Ordered" or "Ordered from Random" so it will play all of the sounds.
"Interactive" gives you other freedoms as well. See this thread for more info.