I am using the high pass and low pass filters. I want to adjust the DB level. I can move the one keyframe I see when I drop in the effect, but I can't add any keyframes. So I can't actually raise the DB level anywhere but that one point which ends up just making a spikey point. Any advice here? Can I add another keyframe in those filters?
I don't think high pass and low pass are necessarily the filters you want, if you're just wanting to smooth out the dynamic peaks and valleys. I used to use a freeware called "Levelator" to treat my audio externally, then drop it back into the timeline, but you get a similar effect in FCPX using the Limiter audio effect plug-in.