Conversation so far:
When did Modern Sounds in Country and Western Music start recording?
The first two sessions were set on February 5 and 7 at Capitol Studios in New York.
When were the later sessions?
February 15 of that same year at United Recording Studios in Hollywood.
Why did he change studios?
CANNOTANSWER.

Question: Who did he work with on the recording?
Self-contained rewrite: Who was involved in the recording of "Modern Sounds of the Country and Western Music"?