I haven't listened to the snippet, but let me hazard a guess: a quintet
by a 19th century woman composer could be Louise Farrenc---but then it
would be not so much Brahmsian as Beethovenish/Mendelsohnian.

Appropos the mystery theme, someone commented that it is easy to absorb
someone else's tune, then imagine that one has made it up oneself.  Hmmm,
that's virtually all I do when I improvise on the piano, except that I
am SOMETIMES able to remember whose tune I started with.  Maybe that is
actually the basis of original composition, except that the composer
draws on and reassembles tiny bits of previously heard music.  Could it
be that "creativity" is really a form of very fine-grained reconstruction?

Cheers,

Jon Gallant
Department of Gnome Sciences
University of Washington