You just asked one of the harder questions
The two subs almost target different applications. The SVS is a big, arguably ugly black box with high enclosure volume and large, highly resonant ports. It produces the most deep bass and seems to outperform the EP350 in a pure movie environment. The downside is that the enclosure and port keep resonating a bit after the signal has gone away, so musical performance isn't as tight. As with every other aspect of A/V system performance, some people hear this effect more than others -- some won't even consider using an SVS for music, others think they sound fine and don't know what the fuss is about.
The EP350, on the other hand, is a smaller enclosure with small ports so less contribution from the enclosure/port assembly. The result is a bit less raw output on movies, but (again arguably) better performance on music. The smaller enclosure and nicer finish also are a huge issue for some installations (eg. a dual-use room where the system needs to look "nice") but in a pure HT environment the big black box might be fine.
Which is best for you ? Depends on how you value (and/or believe
) each of the points above.
Both are very capable subs, each has pros and cons.
EDIT -- just took a look at the latest PB12 (the NSD, based on the PB10 design). It is more than twice as big as the EP350 (~9500 cubic inches vs. ~4400 for the EP350) but it looks like the new port definitely takes the bass response a bit lower. I think everything above still holds but maybe even more so.
The PB10 is felt to be a fantastic little sub for movies but has actually been described as "sucking" for music, while the musical performance of larger SVSs have historically been described with nicer language. I am only guessing, but I expect much of the same will apply to the new PB12.
Like Hsu, Axiom seems to have tried to keep more of a balance between music and movie performance while SVS has tended to optimize more for the movies. As you move into the more expensive models from any of the companies the compromises tend to go away -- it's only at the price ranges we can *afford* where you have to look hard at where each product is targetted.
