You reaction is a proper one. I mean, how can you get 86 Watts from an amplifier that is run from a power supply only capable of 80 Watts? Even at 100% efficiency it's not possible.
Perhaps in the fine print they specify a different supply. How much output do they claim?
You are also correct that using two chips won't magically double the power unless they are running it way below ratings. If they claim 10W with one chip maybe they can get 20 W with two chips.
They are claiming the amp chips continuous power, which is 100W per chip at 4 ohms. (Check the amp PDF file I linked for amp chip specs.)
https://www.amazon.com/gp/product/B096KMY6WW" 2PCS TPA3116 chip, max output power can reach 200W, comes with 19V power supply, can drive 200W (8Ω) or 300W(4Ω) speakers. " Uh, what?
The Chinese electrical engineers that do these amps are no dunces, so I'm trying to understand how they get their power ratings.
Using ohms law (
https://www.rapidtables.com/calc/electric/ohms-law-calculator.html):
8ohms: 200 watts = 40V / 5A
4ohms: 200 watts = 28V / 7A
The Texas Instruments spec sheet says:
– 2 × 50 W Into a 4-ΩBTL Load at 21 V
(TPA3116D2)
Which would be (without efficiency loss added in):
5A
20V
= 100 watts
So yes, the spec sheet is right on.
At first I thought maybe they could under power each chip and get the same volume, but with less distortion, since the chips are not running up against increasing THD, which starts at are round 50% power. But, does that reasoning even work? I mean, 25% power, regardless of whether it is going through two chips or one chip is still the same power and volume, right?