Not sure about this, really. I bought it because I initially liked the effect on busses or the mastering chain. Though, the more I use it the more I tend to leave it off after A/B-ing.
It certainly does give wideness and a sort of depth perception, but it also changes a carefully crafted mix to a degree that I'm not sure I can tolerate: Transients and impulses on drums etc. seem to suffer from the typical stereo widener-effects. While this plug may initially seem wonderful, it just does the typical ms-delay on a stereo source like most others, albeit in a more sophisticated way. I might use this for sound design and fx, but not for a traditional music master that's elaborately done. This is too expansive for what it claims. Sorry, Katz.
Before bashing me here just do this test for yourself:
Take your best set of headphones, put just a kick in one channel and the K-Ambience on the master channel of your DAW.
If you add the ambiente effect as the manual says at 0dB on the Ambience Gaiin Knob it will add a Delay in your sound.
Now turn the Effect off and voalaaa the Kick is perfect again.
Now turn the Effect on and say: Damm what happen to the sound, just looks like there are 2 kicks running out of sync because of a small delay.
On a mastering situation this will really destroy your track. Dont take me wrong i have a lot of UAD stuff. Amperex , Manley, FATSO, harrison, all them really blew me away on the 1st try but this one is really not for me.