You've really got a wide spread of speakers here.
I'm enjoying my Sonata mkIIs, but am frankly driving them with 50W Cary V12. Now, I never come close to using much of the Cary's power, so I think you could get away with 12W. These are 95db efficient speakers. They aren't that small, but I guess about 1/2 the width of the Duos. Still, they take up some room. Watt's are smaller. I've not stood next to the Khorus to get an impression of size, but I think they're a wee bit smaller.
I'm enjoying my Sonata mkIIs, but am frankly driving them with 50W Cary V12. Now, I never come close to using much of the Cary's power, so I think you could get away with 12W. These are 95db efficient speakers. They aren't that small, but I guess about 1/2 the width of the Duos. Still, they take up some room. Watt's are smaller. I've not stood next to the Khorus to get an impression of size, but I think they're a wee bit smaller.