Yes, I noticed it right away and the 996 is even cleaner. Maybe its just the "placebo effect" eg its prolly all in our head - we convince ourselves this is better and we hear it that way.
The sensitivity is much different between the two,which I think has something to do with the audio output.I think the 330 and the 396 use better speakers and\or audio circuits as well.The AGC may also come into play here as well.It seems to smooth the audio out considerably.
As Wyldman pointed out the 330 and 396 have anaolg AGC settings that you can set to improve the audio, but you can get even better sound from an amplified external speaker if you use your radio for a base setup.