You will need to render out to WAV to use Levelator.

yes, .WAV; I use it a lot, but not recommended if you have much music in the track

Usually use to balance out levels in spoken work, interviews etc
The Izotope RX is there if there's unwanted noise to clean up.
But these arealways backups.
Best to record at the correct level in the field away from RF hum, flourescent light hum, traffic and wind noise etc
We can fix it in post, is a phrase i hear often, usually from someone who isn't doing the editing!
But that is always a fix of last resort, IMHO.
Same with lighting and video, always better to have clean well lit images whenever possible.

Levelator is a standalone compressor/limiter program that works wonders to "even out" levels over a long recording.

I use it after I record conference calls over the phone with multiple attendees. Some are good level, some are low, depending on their connection quality.

The beauty of Levelator is that it's like you were riding gain throughout the entire hour long call. It was designed for podcasters to bring levels up as a final step. It doesn't just boost peaks to a predetermined point like the Normalize audio switch in Vegas does.

Levelator analyzes the track and boosts all the lows up. It's best for spoken word, not music.

In practice, I render out a wav or aif file (the only two formats it accepts) then drop it on the Levelator icon on the desktop. Levelator takes its time (it shows a progress bar) and in a few minutes (a short file will take only seconds) spits out a new file in the same folder the original came from, with the same name as the original file, but with ".output.wav" as the suffix so you know which file is which.

I then drop that file on the timeline and proceed. I use it often. And for free, the cost can't be beat.