I want you to look at the TPA3255 datasheet at figure 8:
View attachment 223786
This shows you how much power the amplifier can output at specific input voltages with THD+N of 1%.
Now, let's do the math for all the possible candidates, but first let's assume the power supply are 100% efficient(which is impossible, in reality they are 80-90% efficient) meaning that for every watt consumed from the main it produces 1watt DC.
with a 4ohm speaker:
24V 14.5A: 60W/ch, =>60W/24V=2.5A/ch=5A. We can see this power supply is not limited by current and is able to provide 60W/ch
32V 11A: 110W/ch, => 110W/32V=3.43A/ch=6.875A. Again this power supply is not limited by current and is able to provide 110W/ch
36V 9.5A: 135W/ch, => 135W/36A=3.75A/ch=7.5A. Again this power supply is not limited by current and is able to provide 135W/ch
48V 7.5A: 230W/ch, => 230W/48V=4.79A/ch=9.58A. This power supply does not provide the required current to provide 230W/ch.
Now the amplifier is not 100% efficient, it produces heat:
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View attachment 223791
at 100W(50w/ch) it produces 22W of heat, and at 300W (150W/ch) it produces 53W of heat. And I don't think that the small heatsink on the amplifier is able to provide enough cooling on a closed case with no exhaust air or venting. At best it provides enough cooling for 5W.
At 50W(25W/ch) the amplifier has an efficiency of 80%, which means 50W*0.2=10W of heat is produced. This is twice the amount of heat the heatsink is able to dissipate.
So, my final questions to everybody are: are you planning to cook something with the amplifier? Why do you want 300W if the amplifier is not able to handle that amount of power/heat? And how much power do you really need? 10W max per channel is all you need.
Power supplies are most efficient at 50% of the load. This is their sweet spot. So if you are going to consume 20W(in reality) then use a 40W power supply.
In summary, don't bother with "big" power supplies. It is all about clean power not raw power. A clean 24W 7A power supply with less than 10mV ripple and noise will sound better than a 48V 10A noisy power supply.
You can help cleaning the power supply output with a combination of capacitors to clean the noise(small capacitor) and ripple(large capacitor)
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This is why amplifier have those bulk capacitors to help cleaning in supply voltage, but we can add small capacitors to help cleaning the noise also at opamp supply pins:
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