Multi-channel audio editors?

Any recommendations for multi-channel audio editors?

The relevant title is multi-track audio editors.

There are plenty of them, but Audition/CEP is my tool of choice.

Thanks. I'll give it a try.

Most of them seem to only do stereo.

I don't think so.

Given a 5.1 soundcard it would be easy enough to prototype active crossovers
by taking a stereo wav and filtering it into 5 channels:
left and right highpass for the tweeters;
left and right bandpass for the woofers;
summed lowpass for a sub, with appropriate delays.

Try it, see if you like it.

Of course a Behringer DCX2496 would do it all better
but playing with software can be fun.