"Has anyone heard Casta Acoustics? Would the model "A" specs fall into the realm of great dynamics compared to my Paradigm Signature S2's(V3)?"
The 93 dB efficiency of the Casta Model A bodes well for good dynamics, though I'm a bit nervous about what seems to be an 18 watt power handling rating. But maybe they follow a different convention than we do over here.
What you don't want is, a significant mis-match in the thermal compression characteristics of the woofer and tweeter. When you have that, the tonal balance can change with the volume level. So if the woofer on the Casta Model A goes into thermal compression long before the horn-loaded tweeter, at high SPLs the speaker will tend to sound bright. I'm not saying this is the case, as I don't think there's enough information on their website to reliably judge.
Another possible issue is their use of a diffraction horn on the compression driver. Diffraction horns can have a tendency to sound a bit harsh at high SPLs, in my opinion, but usually not at low and medium SPLs, assuming good system design.
Duke
dealer/manufacturer