@jst Now...
1) As many here point out - and possibly eye-opening for some - this is the [rough] measurement of the actual electrical power "used/consumed" by a speaker to produce not-overly-loud sound (80-90dB) at a short distance (~1m) from a consumer speaker (~90dB sensitivity): from a few tens of mW for test tones to under 0.5W for music.
2) However, (1) this "consumed" power does not equates to the amount of power needed to be produced/output by an amplifier. This is due to a highly reactive (non-resistive) nature of the speaker load - reflected by a high V-I phase - up to 40° at some frequencies, eg,
here. If there is a phase between voltage and current, only a portion of the signal gets used by the speaker and the rest is "reflected" back to the amplifier, eg, see a good
discussion here. So, to provide the amount of power from (1) to a speaker, an amplifier has to produce "power factor" = 1/cos(ϕ) more power!
3) In a transistor amplifier (eg Class AB), this returned power gets dissipated into heat. In our case of a Class D amplifier, this power can cause all kind of issues (like raising rail voltage, see "bus pumping" in the article above). [With a proper design - the BTL bridge mode and large capacitors to absorb returned voltage/power. My understanding, Aiyima does it, to a degree.] Still, to provide the needed "acoustic" power to the speaker, the amplifier has to generate "power factor" more power. And this is not even accounting for the "dynamics" - instantaneous high-power peaks - in the music itself.
Bottom line, as what you really after is just an estimate of your power supply [DC] current
I, I would recommend measuring it in your existing setup. (Knowing the power supply VDC, will also allow you to calculate your consumed DC power, if you are interested. And remember, it feeds both channels.) My bet, you'll find out that for your listening rig, this current is very low (<<1A)! So, any power supply on the market will do its job fine!