What is best Subwoofer for Vienna Ac Beethovens

Good list so far..add B&W to your list...their subs are more designed for music vs. extension...but I have a feeling they would mate very well your Viennas...they have a smaller 8 or 10" that is very impressive...about $1500...and despite what hi-enders think...Sunfire subs are very good as well...cant go wrong with REL either...

Earthquake MKIV 12" sub or even 15' isn't "so large". I also like the M&K's for speed, musicality, and transient impact! These are my personal chioces for HT/music sellection. There's a lot that would work very well out there. But the key is in how well you can set it all up!!! The room placment, calibration, and room/system integration will be more than half than 75% of the equasion for getting world class sound from any sub you chose!!!
Good luck

I used a REL Storm III with my Beethovens for music with superb results. Cannot recommend this combo highly enough.