You wrote :

"SET looks like the way to go but I haven't ruled out other options either."

I know that SET is the politically correct amp to pair with a high efficiency full range driver. But don't rule out the option of higher power SS amps. I also recognize that my opinions are completely different from 99% of the single driver users.

I don't use tubes and have a 200 watt SS amp driving my Lowther and Fostex designs. I am going to be upgrading the amp and preamp soon and will stick with SS. I like SS because it gives the speaker designer a number of degrees of freedom that a low power tube amp will not allow. The combination of higher power SS, passive filters, and full range drivers can work very well. I have not heard any real negative comments from diehard tube users who have heard my system. On the other hand, I have not lived with tubes so my experience is limited to observations I have made reading posts on the various forums dealing with single driver speakers.

Hope that helps,

Martin