Auratones and Yamaha NS10's were in the control/monitoring room of just about every studio I recorded at in L.A. during the 80's and 90's. Some of them also had large Altec "monitors" (Voice Of The Theater) or other 15" woofer/compression horn systems built into a wall of the room. In the 2000's I started seeing Westlake (a Pro sound company) self-powered speakers, and British Tannoy monitors. Smaller studios (including home studios) often have Mackie speakers and sometimes subs.
The vast majority of engineers are not trying to achieve the "natural timbre" and "uncolored" sound audiophiles judge speakers by, let alone the depth and soundstage valued by them. It is a "good" sounding mix the engineer is going for, good being a very subjective and relative term. The timbre and tonality of acoustic instruments (including vocals) is almost always subjected to parametric equalization, compression, limiting, gating, and electronic reverb. Microphones are not selected for their "accuracy", but for their character. For instance, many engineers record snare drums with a Shure SM57, a mic with a deliberate presence peak built in, appropriate for it's intended use as a stage vocal mic.
The final test of a mix is made by playing the new recording and comparing it to a commercially released hit album CD, A/Bing them back-to-back. The idea is to make the new recording sound as "punchy" and "loud" as the CD. The relationship between the frequency response of the monitor(s) and the sound of the recording is not taken into consideration. J. Gordon Holt long ago found that many recordings were equalized to compensate for deviations from flat response in the speaker used to monitor the recording; play the recording on a speaker possessing flat response, and you hear the colorations built into the recording to make it sound natural on the monitor speaker that is itself colored.
You never see audiophile speakers in U.S. studios---no Vandersteen, Wilsons, Magneplanar, KEF, Spendor, Thiel, Magico, or any other brand found in high end home systems. It's a wonder Pop recordings sound as good as they do!