From the way you described it seemed to have happened suddenly and it was obvious enough that you noted a time frame. That makes me believe it's likely your system not your ears as the ears would be more gradual over time. But still a good idea to have checked anyways especially if music is playing harsh that could speed up hearing loss. I think stylus last 10k hourish...also maybe a cable was jolted, like it has back out slightly. Perhaps the tracking or balance of your tone arm has moved? I do notice power around my house like appliances, dishwasher laundry seems to change my sound too almost thin like. But agree with everyone here time to play detective. I'm not sure if you said this but do you have tubes? I'm sure if you did you would have already checked that out. But keep us posted we are all curious to find out the source of this. I've put wharfedale and Naim 5si together and it was a shockingly good combo. Nait 5si may not have quite the power a supernait has but the sound signature is very much the same and wharfedales are easy to push. If you end up exploring this option later thought that might be helpful information.
I noticed brightness/harshness more than usual from my system a couple months back.
My system is not high end by any stretch see my virtual system. A couple months back I noticed brightness/harshness when playing my lp Steely Dan Aja the song Deacon Blues. I had never noticed this before. This is one of my best sounding LPs. I hear it on others too. Sometimes it's subtle, other times it stands out, sometimes I think all is OK. Weird! I never noticed this before. I always liked the sound of my system. Something changed, but what? I am approaching 70 years old and I am wondering if my ears are more sensitive to high frequencies. But anyway I started by checking my cartridge. Visual inspection. Adding and reducing tracking force. Anti skate too. Moved speakers away from and closer to the walls. Cleaned all connections with deoxit. Even sent the cartridge to The Sound Organization to be checked. They did not find anything. I am not able to rearrange my listening area or add room correction. Just nowhere to go.
I would assume if the speakers or integrated were defective I would know it. Something like that would stand out. Yes? I am thinking it is probably a combination of bright speakers, bright amp, bright cartridge and old ears.
So if nothing is broke.... I am considering replacing the speakers would work. Maybe Wharfedale Lintons. I can afford them or something in this price range. Maybe the cartridge? Hana SL or ML. Maybe the integrated? But with what I have no idea. Naim SuperNait 3 caught my eye though I would need to save a long time to afford it. I am retired and on a fixed income. Really fixed! There is nowhere close I can audition any of these.
I realize I am asking alot but any suggestions would be great!