Best subwoofer?

I found that Wilson Audio's demo of the Genelec at last years CES was pretty telling of what you get for the money! Actully don't take my word for it go to Wilson's website under news and views and see for yourself what's actually inside a Genelec vs a Wilson Watch dog VERY SCARY what some manufactures slap together and call it ground breaking or cutting edge !. I don't own a Wilson watch dog or anything i just thought it was a very effective demo.

Revel Sub 30, one of the best. you owe it to yourself to ck this sub out. gets down low. great for music as well as HT

For High-End stereo, try a REL Studio - Its the best out there. Any REL really. Especially the "ST" range.

The REL Studio comes in three generations I, II and III (Linkwitz Riley, ARM and Super ARM loading). Has anyone managed to compare them, ie, is there a significant improvement to consider getting the later generation model? I'm considering to use one with the Apogee Diva's, where both speed and musicality are important.

Perhaps, you should have stated some constraints with respect to your question, such as size weight and cost. This is from the perspective that the best subs out there are very large (as a minimum, think 3' by 4' by 5'), generally well braced and massive (300-500# per side) and very expensive ($10-20k per sub). That is not to say that there are not good choices at other price points and with smaller size. Of the subs mentioned, I would recommend either the larger Audio Physics subs or the Martin Logan Descents. I have had very positive experiences with both, albeit in other audiophiles systems. I have also heard good things about the digital Velodyne self equalizing units but have no personal experience.