Amplifier knobs...where to "set" on the clock?


Here is a question that has idled in my head for years...

I have a 1983 M-70 Yamaha separate amplifier...paired with a C-70 pre. On the front of the M-70 are two sets of knobs for output...for the A and B speakers. I have never been sure on where to place the output line...as if on a clock.  A  "tech" friend told me that the knobs should be at straight-up "noon"...(not wide-open at 5:00)  He saying the reason: "Let the preamp do all of the work". Then, I asked the tech who serviced the M-70 and C-70 years later and he told me the knobs should be "wide open" at 5:00. no reason, except that is where they should be set.

Hmmm.

What do the fine people here at Audiogon say to those two opposing opinions?

What a hobby!

Thank you in advance.

vinylspin
vinylspin
That's good solid professional advice you got there. The only thing better is this documentary, a few years old but still the gold standard in terms of explaining the importance of where those dials point. https://www.youtube.com/watch?v=4xgx4k83zzc
With the volume set at noon, where is the volume set on the pre when listening at loudest levels.