[jakewash]

The Ultra 13 does sound good on paper, I usually try to match the sub to a room size. If you have a really large room the Ultra 13 would be a good bet, other wise the extra power is just extra power.

I had a HSU STF3-MK2 in my meager 12x28x8 room and I had stuff falling off the shelves and it was calibrated to the same SP levels as the rest of the speakers. So room size is important. The EP500 was even worse or is that better?

I guess it also depends on whether or not you like your sub/bass to be dominant over the rest of the system or blend in.

And let's not forget we are talking about sound waves you feel more than you hear.