She made one of the most beautiful recordings I have ever heard, Erbarme mich, from the St. Matthew Passion, a sort of duet with violinist Otto Buechner, conducted by Karl Richter:
https://www.youtube.com/watch?v=aPAiH9XhTHc
Here is an aria from Rossini's La Cenerentola
https://www.youtube.com/watch?v=peuQjyQXCPI
This is a whole recital from 1979.
https://www.youtube.com/watch?v=_cAF3VP4cpo&t=2443s
I don't know that much about Ms. Hamari's career. She started teaching in Stuttgart in 1989, and she is still living. But I think she is a wonderful singer.
There have been many wonderful singers besides the top international stars.
Another singer I came across listening to oratorios with Karl Richter is Helen Donath, who had a very long singing career, and also a teaching career. She also is somewhat younger than I am! But that will be another post. Here she is with Ms. Hamari:
https://www.youtube.com/watch?v=x69mB94G4_Y