Ever changed components in an audio unit?

Just wondering if anyone has ever changed electronic components on audio equipment? Not the whole piece but electronic board-level components (and something other than tuning chips and tubes if you use tubes).

I did it a couple of times in the past year with an old entry-level pre-amplifier. I had sent it in for an upgrade over 25 years ago but due to career direction, it went into storage and wasn't used until ~16 years ago when it promptly crapped out after a very few minutes of operation. Didn't think much about it until I opened it up last year. A quick look at the circuit board revealed that one of the electrolytic capacitors (IC / Illinois Capacitors, who some say made sub-standard and unreliable products in that era) was leaking. Replacing it with a Mundorf capacitor - a 5 minute job because I couldn't easily get the circuit board out of the chassis - got the amp working again.

Working but not great sound (just not very good). Having a look at the circuit board again, I got new around to replacing the 4 other power capacitors (all also IC) with Jensen units (couldn't get Mundorf in the same capacitance values) yesterday. Couldn't get the board out even with medium difficulty so I had to do the same hash job (cut old capacitors out and solder the wires together). What a difference it made however: Trebles higher and more dynamic, more and tighter bass. Clear and livelier sound with more detail overall. I'd like to replace the low-voltage signal capacitors but those will prove much harder without getting the board out. FWIW, electrolytic capacitors apparently wear out over time and especially when not used.

Some would question the value as the 5 capacitors came up to around $150.