There is a flood of different names and terms describing power mini stereo amps, such as “Class D” or “T-amp”. Several of the terms which amplifier suppliers publish often are misleading and do not necessarily give a decent indication of the true functioning of the amplifier. Most home stereos only incorporate amplifiers that have a few watts power which usually is enough for a small room. For superior audio quality, you may wish to go with an amplifier that offers bigger output power than you need as most amplifiers are going to exhibit rising distortion once the audio output power goes up. However, “rms power” shows how much power the amp can deliver for a longer amount of time without being damaged. However, “peak power” can often be misleading since there is no standard stating the amount of time that the amplifier must be able to output this level of power.
Still, whereas the rms rating is going to tell you more about the amplifiers real performance, be sure though that the amplifier offers a peak power rating that is quite a bit bigger than the rms spec. Music and voice signals inherently always fluctuate in terms of their power, i.e. the power envelope of the audio will change over time. This is since at specific points in time the signal is going to show peaks of power which by far surpass the average power of the signal.
Please notice that often the peak power of the amp is going to depend upon the impedance of your loudspeakers which is normally between 4 and 8 Ohms. As such the highest output power is going to vary depending on the loudspeaker impedance. The lower the speaker impedance the higher the highest power the amplifier may output.