I've done a bunch of searching on this topic without any luck, so I won't be surprised if the answer is "No", but is there any way to load a new audio file into a table without causing a pause in the music output and without waiting an amount of time equal to the length of the audio file?

So far the options I've found for loading a sound file into a table are:

soundfiler: fast, but runs in the foreground thus interrupting anything else which is going on

readsf~ + tabwrite~: reads the file in the background, writes to the table piece by piece in the foreground, takes time equal to the length of the sound file (that is, a 3 minute song takes 3 minutes to load)

readanysf~ + tabwrite~: ditto, but with better file type support

Are there any options I'm missing that would do better?

One possible alternative is to us the [readsf~] -> [tabwrite~] approach within a subpatch. You can then use [switch~] in the subpatch to give it a higher sample rate and to turn the subpatch off when you're not using it. Since it's at a higher sample rate, it will read the file in faster. You still have to wait, of course, but you won't have to wait as long and you can do it without interrupting the audio.

If you can get away with preloading your files with [soundfiler], though, that's probably the best way to do it.