In the application range of Bluetooth and Wi-Fi audio, the following matching principles are mainly considered: power matching, impedance matching, frequency band matching, damping matching, and power reserve matching. The most important of these are the first two principles.

Power matching
    Some people often equate the rated power of the power amplifier with the rated input power of the speaker, and believe that only when the two power indicators are exactly the same, the power will be matched. This view is one-sided, because the rated output power of the power amplifier and the rated input power of the speaker are two completely different concepts that cannot be confused.
    The rated output power of the power amplifier refers to the power limited by the distortion. Beyond the level of this output power, the output of the power amplifier will produce clipping distortion, and a considerable dynamic margin must be left. The rated input power of the loudspeaker refers to the limit power that the loudspeaker can work continuously without damage within a specified time.
    The national standard stipulates that the rated input power of the speaker refers to the power of the speaker pink noise signal level, so that the speaker continuous work for 100h without damage to the limit power.
    If a low-power amplifier is used to drive a high-power speaker, the dynamic range of the power amplifier is not enough, and when the speaker has not reached the required output pressure, the power amplifier has limited distortion:
    1. Using a low-power amplifier to push a high-power speaker will appear "push", simply said "push" is a slightly larger distortion when the power increases rapidly, and it is difficult to achieve the balance of the full frequency band.
    2. The continuous output power value of the amplifier is less than the continuous output power of the speaker is the most likely to cause damage to the speaker. Because if the continuous output power of the amplifier is 100W, the continuous output power of the speaker is 200W. When the system is connected, once the volume knob is adjusted and the output power is about 100W, the power amplifier is already in full load operation state. And the speaker has a lot of margin, once the user continues to increase the volume, the output power at this time exceeds the continuous output power value of the power amplifier, that is, the moment the distortion begins, this distortion is called "clipping distortion", in the professional audio industry is known as "speaker killer". This distorted signal, even if the power is very small, can produce an electrical signal similar to DC, which can easily burn the coil of the speaker. For a speaker with a continuous output power of 200W, a 150W electrical signal with a distortion rate
    On the contrary, if the input power of the speaker is too large, it will work continuously at the required output sound pressure level, which is easy to be burned.
    Therefore, the rated output power of the power amplifier is generally required to be greater than the rated input power of the horn.

Impedance matching
    It is ideal that the amplifier impedance is equal to the speaker impedance.At this time, the power amplifier and the speaker are in good working condition, and the power amplifier works in the best load line state, which can give the maximum undistorted power and obtain good sound effect.
    What if the impedance of the amplifier is less than the impedance of the speaker? Like a 4-ohm amplifier hooked up to an 8-ohm speaker? According to the power P=U*U/R, it can be calculated that the output power of the power amplifier is only half of the rated power, at this time the sound volume of the speaker is relatively small, the sound pressure level is not enough, etc., but it will not cause damage to the equipment, so in some cases this configuration can be used, but it is not recommended.
    What happens if an 8Ω amplifier is connected to a 4Ω speaker? At this time, because the actual load is only 4Ω, according to the power P=U*U/R, the current I at this time becomes about 1.4 times the previous, at this time the power amplifier is in an overload state, it is agreed that the power amplifier will be burned.Therefore, you must not use a large impedance amplifier to promote a small impedance speaker.

Band matching
    In order to obtain faster dynamic response and better high frequency characteristics, the frequency band of the power amplifier should be quite wide。generally, the electrical frequency response of the power amplifier is required to be straight, and its frequency band width should be much larger than the acoustic frequency response width of the loudspeaker。the acoustic frequency response width of the loudspeaker can only reach a maximum of 20Hz-20KHz, while the electrical frequency response width of the power amplifier can reach 10Hz-100KHz.