The choice of music isn't going to make any difference - the amps and speakers really don't care about that, and there really isn't any way to design an amplifier to play rock better than classical or vice versa.
Now bandwidth of the amplifiers might make a difference. The M-60s are full power down to 2 Hz. This is to prevent phase shift in the bass region, which can in turn cause a loss of bass impact. The Kensington is a benign load for either amp.
