That's right but signals don't equal immediately a square based on some clipping.
By the other hand I have to say it's indeed possible to get twice the rated power but, a very strong gain is needed and therefore a very strong distorted and clipped sound.
But some audible clipping never equals a square.
So that means the 1.4x calculation is "most of the time" of theoretical nature.
Most of the time the 1.4x calculation is considered on clipped sine wave. But audio signals are very different animals with very high crest.
Considering sine waves are great for easy understanding description. But audio signals aren't pure sine waves.
In the field:
Considering a bass signal that's swinging note is sustained clipped for appro 3..4 seconds and then swinging clean . Probably most folks do the 1.4x calculation on the clipped content. That means doubling the rated output power for the time duration of 3..4 seconds 175 Watt x 2 = 350 Watt.
But the truth is different. The measurement of the clipped signals RMS tells that the power is appro 1/2 of the rated power in this case. That means only appro 80 Watt for the clipped time duration of 3..4 seconds.
Depending on sound settings and playing style and other terms the audible clipping starts at appro 1/4 to 1/3 of the rated power. Thats only appro 40..60 Watt at 175 Watt rated output.
Volume and Master cranked to max setting indeed the 175 Watt may be doubled but, there is a very wide range which has to be considered starting at 40 Watt up to 350 Watt.
IMO it's nearly impossible to predict the power for distorted sounds until the amount of distortion is unknown.
So doing any estimate is like reading in a crystal ball.
Hope that helps.
edit:
a lot of confusion all around amp techniques is based on the consideration with sine waves.
a sine wave don't let you see the nature/physics of bass guitar signals. Althoug a very lot of discussions are based on the consideration of sine waves, the truth is very different cause a sine can't reflect the bass guitar signal.
But most of considerations are done with sine waves, even the rating of output power.
Considering a sine wave tells the behavior with a sine wave but it don't tells the behavior with a bass guitar signal or audio.
Considering only a sine wave means nothing until the results are "translated" into the physics/nature of bass guitar signals (or audio).
Depending on several terms bass guitar signals are different and depending on several terms audio are very different so each "situation" needs it's own consideration.
