Unstability with tda 2002 bridge configuration
The power supply rejection is not very good (25dB at low frequencies).

Run separate HEAVY wires to each amplifier, and put 10,000uF capacitors on each of the VDD pins.

Also, this chip has 80 dB gain. That means a 0.001 ohm feedback resistor, shared in the GND daisy-chain between PowerRTN and input, with 10 ohm (or smaller) Rload, will cause oscillation.

I suggest you reduce the resistance of the GND wiring at least 10:1.

Remember that ONE MILLIOHM of Ground resistance (or impedance) will be a problem, given your open-loop voltage-gain is 10,000X.

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Here is a sketch of the GROUND-as-feedback situation







simulate this circuit &ndash; Schematic created using CircuitLab