I use a power conditioner and power cables that are used in more relevant applications, specifically recording studios. I use two brands of power cables, one is the standard cable used at Abbey Road. The first audio conditioner I purchased, about 20 years ago, was made by a company that is one of the largest suppliers of power-related products to hospitals and schools in Europe, from sockets and power strips to full installations, because their equipment needs specialist infrastructure. They’ve been in business for over 60 years. I still have the unit and they still make it.
For all that, I’ve never studied electronics, never used a soldering iron, don’t know a capacitor from a resistor, but I do know when a product makes a noticeable difference to sound quality.
This is not constant chasing of snake oil.
(a) I had a PS Audio Regenerator because for the products I had and the wiring I had it made an improvement. When I changed products and it made no noticeable difference I sold it.
(b) The change in equipment benefitted from conditioning. I have since completely rewired and changed to a much cheaper conditioner that is equally effective and much cheaper cabling, that seems to be even more effective.
I am pretty realistic about the limitations of home audio as I got to quite a lot of live acoustic music (opera, ballet, recitals), perhaps now only about 75 to 100 per annum, but I did get to 200 pre-Covid. I am fully aware that, even with the limitations of home audio, power products are an important element to a good clean sound.
Your interest is AV, not something I have any interest in. Each to their own. I still like going to the cinema, our local cinema opened in 1912, the seats and decor are original and not exactly comfortable, you wouldn’t like it, but they show good movies and sell nice home-made cake, excellent coffee and herbal tea. It has a barrel vaulted ceiling and good acoustics, better than most modern cinemas.
I rather like that ticket prices had to be increased when they first showed talkies in 1929 “owing to Enormous Cost”, presumably of installing a sound system. The top prices of 2/- is equivalent to £8 in today’s money, which the current ticket price (about $10).
These cinemas were run like conveyor belts, you came in the front and left through a back door as the next audience entered. Probably most people here remember that from when they were kids. I certainly do.