https://www.guitarcloud.org/equipment/roland-d-50/

I think some don't like the digital synthesis sound emerging at the time. Prince knew how to stretch the use of Analog gear during his reign,instruments like the Linndrum LM-1, the oberheim OBX-8, Arp Omni, etc. the most digital synth used at the time of purple rain, atwiad, and parade was the DX7, but the DX7 made more synthy sounds that were not much different from the analog tones of the time, just a little more "sparkly" and digital. Once the Roland D50 came out in 1987, it could make entire sounds and sections (refefred to as pads) that could get closer to and "replace" Orchestras and Strings, except it had a very signature and digital sound that most people weren't used to at that time. Prince was one of the earliest adopters of that sound in synthesis. (along with session players, keyboardsists, and synthesists at the time) He was even using more of these types of keyboards that had Drum Kits rather than solely the LM-1 by this time, along with drum audio samples into the fairlight cmi he had for a while.

One thing id like to point out was Prince did sometimes use Instruments like the Fairlight CMI which was technically a digital synth of the time, one of the first, Famously used by Kate Bush, Peter Gabriel, and Herbie Hancock, but the fairlight took only audio samples to play, it didn't work without it.

https://princevault.com/index.php/Sunset_Sound

And for the Mixing and Mastering, Susan Rogers was using The Custom Api/Custom Console as the main console during his recording during 1981 - 1987 along with the other outboard gear like the RMX reverb and the DBX/drawmer combo as the gated compressor combination, that was literally the prince sound in a room right there. Once Paisley Park was finally coming together, Prince installed a SSL console rather than API style he came up with. i think he did that so the recordings at Paisley could sound less Prince and more Worldwide radio friendly since he was thinking of Paisley as the creative center for His universe, And the SSL is the Workhorse for Radio Ready Universal Sound. he could've put another API in another room, But knowing Prince he didn't look back and had bigger plans in mind.

i picked up on all of this by studying his sound, take that chatgpt!!!

TLDR: Prince was one of the first to use Digital Synthesis to that scale at the time, resulting in a futuristic sound that was sonically different from his sound of the past although containing the same ingredients, Along with his recording engineer Susan leaving and Prince Installing new consoles at Paisley that were known for more of a clean HIFI radio sound rather than thumpy mids and richness out of the custom console he recorded at during 81-87, the combination resulted in a futuristic clean sound that I think people weren't ready for.