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To a point.

Posted by gusser on July 21, 2017 at 06:45:24:
General rule of thumb for measuring equipment is 5x the measured bandwidth. So to accurately measure a 20khz square wave, your scope needs at least 100khz of bandwidth.
And I would say today, an audio amplifier that goes out to 100khz is good but also the reasonable limit. Going beyond the 5x rule is just wasting money and additionally inviting stability issues you don't need.
A popular example is the HK Citation power amps with their video pentodes in the driver section. But there was a very good reason for this. Remember that the Citation uses nested feedback loops. Stu Hegman needed video bandwidth to get the gain he required and keep phase shift low at the same time. But as you can see these were somewhat complicated audio amplifier circuits for the day. The complexity is in the math of selecting those component values.