I have been thinking about Brahms. I have listened to and enjoyed his Third Symphony and his German Requiem.

And his composition output doesn't seem to be as overpowering in quantity as Mozart or Bach.

Here is where I need help.
I know that I should listen or relisten to:
his four symphonies
German Requiem
But is there anything else by Brahms I should listen to? Does he have any chamber music or concertos or song cycles or the like that is outstanding?
