Ralph (Atmosphere) is correct. An amplifier is designed to amplify the input signal with expected 100% accuracy. It is designed to operate with a flat frequency response over the stated frequency range into a designed for load.
There are other criteria, such as input sensitivity, gain, input/output impedance, etc. But that is it.
Some amps are designed for specific loads or specific speakers. Lots of speakers have some sort of wave shaping circuitry in their crossovers to compensate for the peaks/valleys in the speaker's response. This is why buying an after market electronic crossover that wasn't specifically designed for that speaker may not be a good idea. Because the specific wave shaping circuitry isn't present.
An amp designed specifically for a certain speaker, may have that circuity internal to the amp. But, this is very rare.
So, basically, the amp shouldn't care one lick what the signal is as long as it is within the frequency range for that amp. The amp's output is suppose to be flat. Basically, the input signal amplified. That is it. Doesn't matter the genre of music.
Of course, "tuning" an amp to sound a particular way is another matter. The designer is actually adding circuitry into the amp to force the amp to reproduce the signal in a matter different that just amplifying the input signal. Some add way too much lower end response (bass) or mid range or high end boost. But if you graph the signal/frequency response of that type of amp, you will see over the frequency range that it is most definitely not flat. Basically, they cheated.
An amp's output should be as flat as possible over the expected frequency range.
Again, it doesn't matter what type of music is being played.
enjoy
