Ryder, Fast articulate bass. The bass drivers are tight and when you get them to move they can drain power supply. Depends on your listening level. I have a large room w/ 10' ceilings and love what stereo subs can do for imaging.
In a smaller room with the right amp they can give plenty of good musical bass. The 936 can be driven to 30Hz but can rob too much power from the mids and highs. The speaker becomes more forward and not as relaxing as they can be made. I really feel that a high powered ss amp with a good tube pre would be a good match. I am sure there are a lot of good combinations and I would put a lot of thought into the amp. Two subs just gives me a lot of flexibility and are great at any listening level with all types of music. I bet the bass drivers are rated at 88 or 89db and the mid around 90. Two 8" bass drivers at 89db effeciency can drain a single power supply pretty quick. The effeciency of the speaker may be 92db but they sure don't act like it.