Avery Fisher was active in chamber music in an unusual way: He had a
large library of sheet music and a wide acquaintance among musicians.
The musicians, many of them famous, would drop by in various combinations,
and Fisher would dig out music appropriate to whatever instruments showed
up (for pianists, there was a Boesendorfer on hand).  Much of the music
was unusual, so often his guests would be playing stuff they had not
played even heard in years -- if ever.

Or so he told me when I interviewed him.  i can vouch for the sheet-music
collection and the Boesendorfer, and that the latter was was kept in tune.

I believe he also played a bit himself, but I forget which instrument.

-Ivan Berger