What makes a good amplifier?
An amplifier amplifies an analogue input signal fed in frm an external signal source in such a way that it is output again with higher power, but with the same timing. The actual signal is not amplified, but reproduced. The output signal is therefore output with higher power, which must be supplied by an external energy source such as a power supply unit.
Linearity is of particular importance with amplifiers. Any deviation, e.g. the doubled input quantity does not exactly lead to a doubling of the output quantity, results in undesired values - called distortions.
Look for powerful, accurate instruments of various types with and without external amplifiers.