Full Range Drivers

To get the most out of a single driver, you also need a huge, sometime elaborate enclosure.
And yes, the best can run some real $$$. But, given the generally high sensitivity you won't need a gigantic amp.

You may want to consider this article::

http://www.passdiy.com/pdf/cs-amps-speakers.pdf

These speakers work BEST with current source amps for which Pass provides a workaround.