im in the process of getting defro13 reactivated and then i will give you a detailed explenation of my listening tests..........dave

 

the biggest advantage to put it quite simply is extended low frequency response and power handling as well and excusion control if your tuning low....with a speaker in ib all you have controlling the cone is amp and the speaker suspension, with adding a box and vent you gain even more control over unwated non linear excursion, a high order highpass crossover is also very important when using a vented box.....better control over the cone at low frequencies is always desirable and will benefit the midrange bandwidth as well....again a desrieable thing......