In the olden days, an orchestra wasn't always around the corner, and radio and other mass communication methods were definitely scarce on the ground in the early 19th century. But what there was was a blooming publishing industry, where sheet music was sold to people who liked to play the music but had no access to orchestras.
Herr Hummel, himself no mean pianist, arranged 7 piano concertos of Mozart, and, to top it up, also the Jupiter symphony for a quartet, consisiting of piano, flute, violin and cello. These we have recorded and are now bundling the 4 CD:s into a package at half regular price, making it possible for you to acquire these well over 4 hours of splendid music and musicianship for a bit over 18 Dollars. Fumiko Shiraga (who really has specialized in this - she also has Chopin and Beethoven concertos for the same kind of groups) and her fellow musicians really make a case for such arrangements.