What you just described with the 16-46 is the same that I experienced with the 20-39PC+ and PB1+...possibly to a lesser extent because the Plus subs have a nicer driver. Your example I think does a better job at describing what you heard. A friend of mine described it as "the attack transient and subsequent decay are not clean".

From what I have been able to read, the SVS Ultra subs are better at this.