Have had power supply electrolytics changed in my 15 year old Audio Note OTO SE. These are 220uf 450V and there are 4 on the main supply, they have need changing starting in year 7 and about every 1-3 years, none of the new ones have failed by year 15. When they fail the sound gradually goes hard and edgy, usually its really smooth.
After the change the amp sounds just as bad, initialy I thought the fault hadn't been sorted out. I was asked to persevere for 100 hrs. By end day 3 at 72 hrs and no change I'm thinking it can't be the cap that was faulty, carried on somewhere between day 4-6 it all changed (80-100hrs) the sound went beautiful again, smooth as it should be.
I had 3 done by Audio Note, the same story each time, between 80-100 hrs they suddenly sweeten.
I've now changed the replacement Samwha caps and the remaining original to Mundorf 200 twins caps. Superior to both the originals and quite a bit better than the replacemements.
They don't fit on the board physically so you have to build another mini board to sit on top of the original.
They where immediatley impressive, crushing bass power, better background, sweeter. They came good after only 20 hrs or so and continue to improve, now at about 100 hrs.
Strange thing is testing the the old caps they are 200uf v 220uf stated (at +-20%), the ESR is within the normal range, I have to read up more to find out whats happened, but changing them brought me the return to the good sweet sound I have always loved in the is amp.
