I am using this DC regulator to get 5V to power the Bluetooth. Maybe the difference being mine is not "isolated". Thanks for the suggestion. Might try it the next time I place a Mouser order. The Knacro amplifier does have a 5V output but I found it was only providing 1.5V most of the time and not powering up the Bluetooth. I did not notice any noise when using my Google Chromecast as audio input.

I would estimate build cost was $150-$200 although I have some material leftovers for future projects. ;)

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Not sure if that’s considered advertising, but this is the regulator I installed for May 12v fans. I’m not affiliated with the link. Just recommending the product. You can solder a pas on the back to select the voltage output.

5v Regulator, DROK 5pcs Mini Voltage Reducer DC 4.5-24V 12V 24V Step Down to 5V Buck Converter Board 3A Volt Step-Down Transformer Power Supply Module https://www.amazon.com/dp/B0758ZTS61/ref=cm_sw_r_cp_api_i_r6kDCbFAJCCR3