I use Green Mountain Audio Diamantes that are a quarter wave transmission line. The speakers are cast marble and two pieces each. The upper part contains the speakers and crossover while the bottom/base contains the folded network for the transmission line. The tube is many feet long and filled with long fiber sheeps wool to slow the air flow. I have experimented with slightly changing the damping by altering the length/amount of wool by only 1.5 ft or less makes a very noticeable difference. I had some left over from an update from series 1 to series 2 many years ago which also had a crossover change included. The speakers are rated at about 87db but sound best with a lot of power and cranked up loud like over 90 db average. The bass is very quick and dynamic, no residual warmth, extends to the low 30hz range in my room but very little below that. It is a very different sound than my B&W's.
