I built Basszilla Platinum speakers. I has two pair to Fostex Sigma 168 speakers and used them in a MTM configuration with the Aurum Cantus G3si tweeters. I had to do a couple changes to the crossover to adjust for the impeadance change from using two midtrange drivers. I use a NTH X1 crossover for the bass to midrange crossover. Using Paramours with 2A3 tubes the speakers can play at more than realistic volume levels. The sound is fantastic. I moved them to the number one spot replacing Magnapan 1.6q powered by a Class A solid state amp.
I modeled the baffles from the original plans using the design of the Infinity RS models. Attached are pics. I am a believer in the Basszilla approach. The sound is fast and airy with good imaging. I have never been able to find a satisfying efficient speaker before this.
Chuck