I heard the active DEQX versions at last year's Lone Star Audio Fest, and they were very impressive. I have no idea how the passive version will sound, but I am familiar with the CSS drivers used in this design and they are among the "best behaved" extended range drivers I have heard. Their response is flat across the spectrum up to about 10khz, and their Xmax is about 6mm, giving them exceptional bass capability for a small driver. There's almost none of the 5khz to 7khz breakup that's characteristic of many other high quality midbass drivers, so I would imagine the passive version can be implemented with a fairly simple crossover that doesn't compromise the sound.I'm hoping Jim will read this and respond, but if he doesn't you could contact him at jrgriffin@cookeville.com