First Watt SIT-3 proper speaker matches

I have a SIT-3. I understand that it mates best with 4 ohm loads. I’m trying to find out if the amplifier is compatible with some 8 ohm loads. I am considering the Focal Kanta speakers that are 8 ohms and dip down to 4. The Focal Sopra 1 have been reviewed well with a 12w Valvet singled end solid state. I know there are other factors aside from impedance and efficiency but I’m not clear on the topic.