I agree with @soix . Tube power is not likely to be the best choice for money spent on these speakers. Those power reccomendations are for standard 8 Ohm power ratings with the assumption that the amps can double down with impedance. As a bare minimum in a small room I would suggest ( as 3 Ohm ratings are the exception ) 200 Watts into 2 Ohms, and in a room of your size; double that or more. The power rating into actual impedance is more important than the 8 Ohm rating. Be leary of amps suggesting "stable into X impedance". Such a statement only means that the amp won't go into oscillation when presented with such a load. It does not suggest power output or distortion levels there.
Thiel CS1.6 loudspeaker Measurements | Stereophile.com
These are lovely speakers for smaller rooms. You can probably get more from larger Thiels in your room.