I have done lot of research on this. I can not come up with a European driver. Pretty much all that I have designs for have been discontinued. The European manufacturers have reduced their catalogs.
In addition, particularly in Europe, there is a marked trend away from high Qts. drivers.
This is a trend that on the whole I agree with.
In the USA, as I have pointed out many times, there is this unhealthy preoccupation with the lowest F3. This war has come at the expense of bass quality. I can hear this when I listen to a lot of American subs. They may go deep, but the quality is often awful. This is not something that shows in standard measurements, but it sure does when you play it in your room, and especially in the smaller the rooms with the high Schroeder numbers. European rooms tend to be smaller than American rooms and so the deleterious effect of high Qts subs are all the more apparent.
Anyhow, I think you are best off using this
Dayton driver per your specs.
As it so happens I have a design on file for this driver, and fully worked up, for a 12" sub that would be a very nice sounding sub. It is one I think you would be very pleased with, as you can see from the models. The size is also very practical. I actually worked this up as a design I plan to build for our family room.
I think that will be a very high value sub, that you would be very pleased with.
