Why don't upgrade the wires and components inside our units?

 @vanson1 In my opinion, you could not be further from the truth in your statement thet "there is much more to be gained there". And there is certainly a lot of low hanging fruit to be had to this end especially if you have some basic mechanical skills. It's not that hard. (seems like you already may know this). All my amps have direct wired DH labs silver copper AC all the way to the fuse block. I use mil spec ptfe insulated silver tinned copper inside and honor the wire gauge of the original design. My experience is with 1980's 1990's vintage high end gear and have had amazing results along with mods based on long standing consensus in the DIY community as to the efficacy. Just be forewarned, opening the cover can lead to a deep rabbit hole. @larryi I appreciate your direct experience with a certain mod, but those that mod either for themselves or for business would stop doing it or be out of business if it was not highly effective.....

Peace

I upgraded my interior wiring and speaker post on my vintage Klipsch Cornwalls, made a HUGE difference, bigger sound difference than anything else I did to  them...

Wires, unless they are corroded or burnt, do not get 'old' and do not need replacement.

Semiconductors do not need changing unless burnt.

Resistors are about the same.  Leave them alone unless burnt.

About the only thing worth changing are the capacitors, especially electrolytics.

If you have them, another type of component also worth changing are relays and mechanical switches.  Their contacts do oxidize and changing them may be a good idea.

If you have surface mount components, this whole thing becomes a difficult task.

I started with my Cornwall’s, LaScala’s ll & now ready to do my Chorus ll. All with 18g & 16g OCC silver on top & 12g OCC Copper on the bottoms. I tried both ways & seem to like my current way. Really made a substantial difference.😃

Warranty and resell issues prevent some. Murphy prevents me as him and I are firm friends.