Will adjusting monitors color settings without the use of a hardware calibrator degrade image quality ?

[xMax]

will changing the brightness and color temperature to a new setting degrade image quality, such as gradation smoothness and grayscale accuracy(additive color mixing), and thus require that i use a hardware calibration device when changing the settings to keep the image quality in tact. or is a hardware calibrator only required to match the monitor to a target, such as another display, scanner, or printer.

thanks.