[RadioKid]

>Is sou ka considered to be rough, male speech?

Yes, Generally.

There are two types of "SOUKA". One is acceptive (or self talking) and another is suspecting (or not believing). I'm not sure if it is like the use of "really" in English.

Even girls use "SOUKA" in the acceptive use sometimes. Sometimes girls say "SOKKA" instead of "SOUKA" in accepting use.

>I ask because I've learned that using か to ask a question without です is typically considered blunt/rough male speech.

Yes. Because "DESU" expresses polite mind, conversation will be rough without it.

>そうだ。　　Sou da. 　　- So it is (casual? rough male speech?)
very roughly, it is casual and rugh. But there must be another explanation for it. I can not figure out right now.