i had a 410T and it thumped! i tried a tvx once it was very disappointing in comparison. i think the difference in the sound comes from different drivers as well as a different port location/size
the 410T i had was 4ohm and had 16 ohm drivers in it with a rear port in the middle of the box
the tvx has 8 ohm Sheffields and a front port at the bottom if the box
i'm not a scientist so i cant say why....but the older ones just sounded better to me despite the "inferiority" of the drivers
kind of a moot point since i have 2 3620's now....
MUHUWAHAHAHA