Decision between Zu Definition OR VS DB99

To those who have both Druid and Definition, allow me to state the obvious assumption (hopefully true), that any comparisons you make are done in the same room with otherwise identical equipment, etc. As bass response is very much the issue here and it is highly affected by the room, I am sure you have nullified this variable, but just wanted to be sure.

I owned the Druids and upgraded to the Def's. I've compared in the same room with the same equipment. The Def's keep the strengths of the Druids (speed, immediacy, tone) and add deep bass, even more power handling, a more refined top-end, and a bigger soundstage.

But, the Druids are spectacular in their own right. This isn't on-point to the VS vs. Zu so I won't elaborate - just a response to previous question.

I have a question about the Druids. From looking at their pictures they look thin. They look like sound panels. That and from what I read in the past about one cone drivers that combination does not equal a very loud dynamic speaker. Compared to maybe Paradigm v100 or Silverline Sorino or VS-4 JR's. The weakness of one driver to do it all was they could not play loud. From the looks of things I get that impress with these. They seem to me to be very nice speakers. Reading the litiature of their website says that these speakers do play loud. But how loud is that?

I have new Druids and I can tell you that they will play louder than anyone should listen. Loud enough to damage your hearing.
This is the most original, engaging and exciting audio product I have ever bought in 30 years of perpetual experimentation.
They are fast and friendly, clean and rhythmic, magical in their presentation, and modest in their requirements. High efficiency combined with high power handling capability opens the door to any amplifier you care to try.
I would say that comparison to electrostatics might be more apt than comparison to conventional cones. The Zu Druid will leave that stuff in the dust. I replaced Goldmund Dialogues, one of the all time great designs and one of the fastest cone speakers ever with these Druids. The speed and ease I now have make the Goldmunds forgettable.

I felt I was gambling when I bought these Zu speakers but I can tell you that there is no gamble involved. Try a pair.

Greetings
I have an AA Capitole CD and Capitole Power amp. I am expremely happy with both.
I believe that you will need to set the Capitole CD volume control around -45 db to listen at average levels with 100db efficient speakers.
I find that below -30 db, the Capitole's analog volume control has a slight loss of transparency.

You may want to look into a Modwright 9.0SE remote-controlled tube preamp. Its signal to noise ratio is excellent, more than 120 db (outstanding for tubes) and it got rave reviews.
I am buying one, together with a pair of Zu Druids. I believe it makes sense to control the overall system gain and improve the S/N ratio.
Good luck on your speaker hunt!