Connecting TDA7293 in parallel

I bought this "xh-m210" tda7293 board from aliexpress tried connecting it in parallel, sound gets distorted and start to get hot really fast.
1. How can I connect it in parallel?
2. How can you make this board better/ sound better?
 

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Look at the schematics in the datasheet for a start - it's probably very close to that. Then you'll also see that you can't just hook up a stereo amp in parallel, especially not for the TDA7293 - you would need to modify the PCB for that.

As for how it can be improved, you'll need to trace the circuit + component values and show us before it's really possible to make any worthwhile suggestions.
 
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From my experience ordering boards like TDA7293 or LM3886 from China there is a chance that those chips are not original TI or STMicroelectronics.
Let's assume you have original TDA7293 chips. In that case, the issue could very well be the incorrect schematics that can result in incorrect board layout. You would need to reverse engineer the whole thing to see if there is an issue with the schematics.

Assuming schematics is correct, you have to see maybe there is layout mistake. Things to look for would be decoupling capacitors close to the chip, or inverting input pin traces as short as possible.

I tried powering the chip with linear power supply and used transformer with 28V-0V-28V secondaries and TDA chip got too hot. Now I am using transformer with 25V-0V-25V secondaries and the temperature is not too hot. You get around 37V and 33V DC from those secondaries btw.

I have put together amp with two TDA7293 in parallel using the modular schematics from the datasheet and it has been the best sounding amplifier ever! THD is around 0.002% if you put two of them in parallel!

In fact it sounds better then two LM3886 that I have put in parallel. The issue with LM3886s is that they don't have same option as TDA7293s to bypass input stage and VAS so I migh just keep trying different approaches with my LM3886 amp.

Good luck and hopefully you'll be able to trace the issue and enjoy the amazing sound these chips can produce.