40-50w tube amp for Aerial 9

I heard the new Dehavilland 50a at RMAF and just loved it. Dehavilland says it is nominally 40w, but practically closer to 50. I have concerns that it will not have enough power for my Aerial 9s (which I also love). They are 90db sensitive (pretty good) and have an impedance of 4 nominally, 3.2 minimum, low resistance (while I know the impedance is a factor, I am not sure how to apply it in this context).

Anyway, has anyone powered their 9s with this amp or a similar relatively low power tube amp? Anyone have any other thoughts on compatibility.

Thanks much.