I don't know if its is good news or bad news, but, many older recordings remain among the best sounding recordings ever. For big band, try listening to Duke Ellington's "Blues in Orbit." This was recorded in 1959, in stereo, and remains one of the best sounding recordings. When Sony launched SACD's it was one of their first such issue because of its sound. I have the SACD and the original 6-eye Columbia vinyl issue; the vinyl original sounds the best.
Another really good sounding big band recording is a direct-to-disc recording on M&K Records by the Bill Berry Allstars called "For Duke." these Ellington covers are terrific sounding.
I also like an album called "Dizzy Gillespie Reunion Big Band" which is a 1968 recording from a live concert in Berlin. I don't have an MPS original, but, I have a very nice sounding reissue that Linn Records (the audio company) put out.