Onhwy covered it mostly. Recording engineers are looking for detail--not the ambience that most audiophiles are. In a typical listening room 50% of the total sound field can come from indirect or reverberant sound. In a studio, it's less than 10%. Near field and much shorter reverberation times. To me the studio sounds very dry and analytical--but that makes sense as it is a tool for a recording engineer to do a job. Whereas when I sit and listen I want to relax and be entertained.
So to answer your question--I highly treated room--not just absorption, that will affect the high frequencies much more so than the midband. It must be balanced. Also, control rooms are generally small with smaller speakers that tend to not produce too much bass energy and have room modes creating acoustical problems. Many studies have large Helmhotz resonators built into them to account for this. Lastly, speaker placement should be nearfield so that the direct sound makes up almost all of the total sound of the listening experience.
So to answer your question--I highly treated room--not just absorption, that will affect the high frequencies much more so than the midband. It must be balanced. Also, control rooms are generally small with smaller speakers that tend to not produce too much bass energy and have room modes creating acoustical problems. Many studies have large Helmhotz resonators built into them to account for this. Lastly, speaker placement should be nearfield so that the direct sound makes up almost all of the total sound of the listening experience.