It doesn’t get better than an evening of Brahms in Manhattan, and that’s what patrons of The Chamber Music Society of Lincoln Center enjoyed (Allegro non troppo from the Piano Quintet in F minor, to be precise) at the society’s spring gala last Tuesday. The black-tie event in The Appel Room at Frederick P. Rose Hall honored Frederick Iseman, founder of CI Capital Partners, and board chairman Peter Frelinghuysen, while raising more more than $1 million.