All great responses! Where to start! Testing specs don’t really show much. Distortion is low in vintage amps and modern gear. Noise floor has improved with preamps. Transistors in well made vintage amps had carefully selected transistors. transistor quality control was not as good as today. They tested matched transistors for each amplifier for high performance. Upside of the times.
Today they don’t, good enough mindset. Now there’s class D etc.
Kenwood KA-5500 is a great sounding amplifier! ST-70 I was never big fan. Same with the Mark III mono blocks. They made clean tube power, affordable or used to be lol.
Pioneer SX828 is great sounding unit. Favorite receiver from Pioneer to be honest.
Sansui makes some great gear too!
I’m not one to replace resisters for no reason. Capacitors I do change, in theory there supposed to sound like the specs. Tired caps change the sound as new production caps would. All part of the fun. When I recapped 7T, earth shattering change. I kept the resisters, changed the diodes, caps etc. Made such a huge difference. Transistors used in the 7T were selected for performance, no reason to change those ever unless there noisy / failed