You know, the small things that can save you a lot of money. I’ll start:
You can get “hospital” powercables that are completely shielded for 20 bucks or so.
You can get anti vibration pucks for washing machines instead of spending 10 times that on the same product which is just labeled as “speaker pucks” instead.
Yes, owner worked on audio repair his entire life. His brother was left to clear his estate and the brother designed audio circuits his whole life.
The brother who did the repair and initially owned it upgraded caps, added further isolation and other items to make it better than spec. Original manuals and all too.