It is a physically separate adapter, but the plug they use is a combo XLA and 1/4" plug. The 1/4" plug is wired separately from the XLR and is unbalanced.
I don't quite understand that. An RCA connector is going to be unbalanced in any case, isn't it? Are you saying that if I use a passive adapter to plug RCA into the XLR input it will be an unbalanced connection? Or that it won't work at all?