Hi - tried using this effect on a wav file over the weekend (Effects > dynamic > -12db soft limit). I like what it has done, but love to know, WHAT it is has done and why it has ‘lifted’ the sound…
That’s a preset I haven’t played with much but I’ve taken a look and wow use it with caution 
Essentially, what is happening here is that any audio that goes above -12dB gets compressed 120 times to 1. Yes, a ratio of 120:1!
I guess it’s named soft limit as it still keeps your waveform dynamic enough not to warrant the name hard limit (which cuts any audio at a certain dB level).
Even more interesting is that Soft Limit -24dB has a threshold value of -24dB, the same ratio of 120:1 and spline curves enabled which gives a soft knee compression instead of the hard knee you get with Soft Limit -12dB.