I had the second character, it means house. Now, I can find the first one... or piece it together, as I have had to do before. I'll link it here when I get done, in case anyone wants it.
"House" is only one of the many meanings this character can take. Another is "family", and another (the one involved here, I assume) is "expert", "specialist", "master of one's trade or craft". This suffix is used, for instance in the Chinese words for "writer", "calligrapher", "dancer", etc... The first character means "ancestor". "Soke" should therefore mean something like "ancestor master".
I might be mistaken though, because the meaning of a given kanji / hanzi can sometimes vary from Chinese to Japanese.
Hope it helped anyway...