The Monolith doesn't go deeper but it does go louder below 25Hz, albeit by 4dB, and it does manage it with less distortion than the Servo. That last bit is surprising considering the volume limit at those frequencies is imposed by the servo's response to distortion.
As far as I can see, the specs of the two are nip and tuck for differences. The only thing I can think of that would make the Monolith a better music performer is the fact that sub 40Hz, it has much lower group delay. That's also surprising because conventional wisdom thinks that ported boxes are poor in this respect. It's not true in this case, presumably as a result of the Servo's hefty EQ in this region off setting is sealed box advantage.
I think it's easy to dismiss this comparatively misunderstood measurement, but doing it well is the one thing all alledged musical subs seem to have in common. The Monolith was better with music in my room than the Ultra which measures better in every respect, except this one.
FWIW, I still think going from a Servo to a Monolith looks like a sideways step and would invetsigate EQ before jumping in this direction. I think the performance gains would be greater as the rooms input would far outway the differences between the subs that can be found outdoors.
Russell
