Just an idea, to have two messageboards instead of just one “off-topic” board… one for music/gear related stuff (which isn’t really that “off-topic” to renoise) and another one for completely off-topic stuff like the latest football match, cars/vehicles, movies etc etc…
If you look at this board closely you notice that only few main branches has sub branches.
Music gear can also be discussed in General or Tips and Tricks or Help,Support and 
section. In the latter two it usually is Renoise related, but i personally don’t see any problem if music hardware is discussed in General without it addressing Renoise.
So in that regard, i don’t see any need to split the offtopic in sub forums. It doesn’t matter for the “view unread/new topics” filter anyway.