Perhaps time to give a bit of feedback on this design, Evocateur. (Also, in light of Nirvana's question about what speaker I listen to whilst working on the Vivace. )
I have been listing to this basic prototype now since November that I put it together. Initially is "spoeg and plak" a design together in my excitement to test the drivers and with time I then more systematically measured and simulated a crossover, build it and listened to it again. Probably 3 or 4 iterations, with refinements on each. Steadily I got on top of the midbass and I has been able to blend it with the Mundorf AMT that I had for a while but never used.
The 8inch(230mm) mid-bass is a stunning unit. It is easy to work with and the sensitivity translate to an amazing experience with the Pathos TT 25W Single ended hybrid, The Ongaku 211, the Pathos Classic One, The Pathos classsic Remix, Pathos Logos, Audio Analogue Pucinni SE and a vintage Marantz 2220. To my ears, the 92db/w/m and nominal 8 Ohms impedances relates to an ease of presentation, impressive dynamics shifts, strong jump factor and very satisfying bass response to the middle 30Hz. I have changed the working volume that the driver sees and also tried a few variations of port tunings. Like always it is a balance between extension and quality. With a bigger volume, close to 40 litres, the extension is very very good for such an efficient system, but the transient speed and attack is compromised. At close to its ideal operating volume 25-30L the quality of bass is better obviously sacrificing some extension. Coupled with these changes the main inductor shaping the roll off of the unit can also be changed to have a bit more full tone or a more critically aligned sound with a flat transition between the upper bass and midrange. In the end, these choices will only be settled once we are ready with the cabinets.(at the moment we think that we will use the same cabinet although less volume utilised for this design than what we will use for the Vivavce-hence the pressure to get on with that process)
The midrange roll off of the driver is very well behaved, and I am very happy with the crossover topology. In this sense, this driver is a beauty. The kind of driver that a good designer can create magic with. No need for a hard handed and interventionist approach, no notch filters etc required. The off axis energy is acceptable and for a dedicated music system very good at the designated crossover point and more borderline for a wide dispersion design.
The more I listen to the AMT tweeter the more I like it, and I would probably stay with it in this design. I even am tempted....

, no maybe not, to change the Vivace's design. It is indeed a very clean, clear and harmonically rich high range, and with more dynamics than what I hear from a silk dome. I will use a bigger version to the 23cm unit I am using now, to improve the low-frequency extension.
Only Alan Hobkirk has been privileged to listen to the prototype. His comments were around the ease of presentation, the very solidly sounding midrange, voices are grounded and has more foundations than most smaller 2 ways(5 and 7-inch designs) and he also commented on the dynamic ability and drive of the system.
So in the end, I would say that I prefer this design with the Pathos TT, whilst the Ongaku replica made the Vivace sound at its best. It is interesting finding and only a preliminary impression. I think the TT really like the sensitivity of the Evocateur and the Ongaku has a more bold sound, that make a slighter lower sensitivity speaker sound a bit more dynamic. The impedance curve of the Vivace is very good for a 3 way, but the 2-way design is even better in the final analysis and it could also be a reason for my impressions between the 2 designs and speakers.
I still would obviously compare the 2 design side by side in final versions, but at roughly 25%-30% cheaper to build I think it might just be a gem for people with low powered amps. It might become my own reference in my system if I am finally convinced that it can match the Viviace's brilliant mid-range ability.
I really like the sound even with its much-compromised cabinet at the moment, it provides me with lots of pleasure and is probably close to the best I have heard with the Pathos TT.