Hi mate,
Do a favour to yourself, open one of your monitors and do a BOM (bill of materials) that you need for the repair/upgrade just to be 100% sure.
Take note of the uF and volts of every capacitor, buy those thar are rated 105C, they work longer than 85C for obvious reasons (inside the monitor gets hot!)
On the power section try to use as much as possible good film capacitors like panasonics, specially replacing the old mylar green caps on those the sound depends and ceramics are excellent for PSU filtering but a bit harsh for audio.
I wouldn't mess with the opamps, they are just fine in that circuit and faster opamps without adding extra decoupling capacitors might bring some unwanted high frequency oscillations.
If you can replace all the high watt resistor by metal film that would be great, as termal noise is something to be avoided.
Take care of measuring diameter and pitch of electrolytic capacitors (here size matters!) and buy from reputable sellers like Mouser, Farnell, TME, Digikey, RS, etc, depending in your location.
I have an old pair of KRK Rokit V1 from 2007 about 18.000hs of use and the power supply caps were very bad (original caps are very cheap chinese and most of them were out odf specs).
After removing the whole black glue I replaced all the electrolytics by Panasonics and Nichicon, and the 100nF by Panasonic and Wima. Also some resistors. Now they work as they should, after more than 15 years of using them in my job every day I am so used to their sound that I really was missing it.
Bytheway, Neumann KH120 have the same power IC, I saw a pic of the inside, just the version for 60volts and they have a regulated PSU (I believe) ofcourse drivers maybe better and other plus like dacs and room correction circuit, but KRK are like standard sound on home recording studios, I love mine.
Good luck!
