I just fired up my new project Solstice. Coming from a Starlight it is a noticeable improvement in sq. Richer, fuller, warmer sound that is very smooth on top. Bass is solid. Details are still present even with more of a "tube" sound overall (to my ears) . Much nicer sound than my Starlight, and I like it more than my Polaris. I have not tried the Ember, but Jeremy says the Solstice sounds more like the sunrise 3. Very nice amp.
I am inexperienced with amps in general, have the Starlight, Polaris, o2 and Magni. So take my comments as such. YMMV, IMHO, etc:)
You have a nice selection of amps. What opamp and tube were you using in the Starlight when you compared with the Solstice?