Hi,
The SE designation simply reflects a slight change in the molding of the speaker's edge--a change in production that doesn't affect acoustical performance. Instead of being slightly rounded, the edge is more angular.
Selecting a subwoofer relates closely to room volume (dimensions) and your own personal taste as to how loud you listen as well as the dynamic capability at high sound levels of the front left and right main speakers.
For an "average" living room--say, 17 x 12 feet--if you were using the Epic 50, the EP-175 would provide lots of low-bass information and high enough bass levels for a room that size and for most listeners.
On the other hand, the Epic 60, a large multi-driver main speaker would be more appropriate in a larger room, or for listeners who prefer clean, very loud home theater levels; hence, the larger choice of subwoofer, the EP-350. It would nicely match the dynamic capabilities of the Epic 60 in a bigger room.
Without knowing your room size, I'd suggest the EP-175 would satisfy your requirements for home theater and subtle, low-bass support for music. If your room is very large, I'd go with the EP-350.
Regards,
Alan Lofft
Axiom Resident Expert
