48V 10A Universal Switching Power Converter Adapter Transformer Regulated Supply AC to DC LED Driver 480w for CCTV, Radio, Computer Project

If you're in a DIY mood, you can build something for a lot less than the $180 price of the Dayton plate amp ($180). You can get a 48V 10A power supply on Amazon for $27: https://www.amazon.com/REALSUN-Universal-Switching-Converter-Transformer/dp/B096VJMQFM That comes out to about $55 for the amp and power supply. You can probably reuse components of the existing plate amp, like RCA and AC input connectors, if they're accessible. You wouldn't have the auto on/off function, but a class D amp doesn't use much power with no audio input, so you could leave the sub amp powered on all the time. The switching power supply might consume power, however. Maybe use a controlled power strip to turn on the sub when the TV is turned on? https://www.amazon.com/ECG-7MVR-Energy-Protector-Autoswitching-Technology/dp/B0058DHO1W