How and why: Installing a 12V trigger in a cheap TPA3251 based amplifier from Audiophonics | Audio Science Review (ASR) Forum
Low Voltage Trigger Module - PAC
TOPPING EHA5 Electrostatic Headphone Amplifier XLR/TRS/RCA input 146dB Dynamic Range 700Vrms Output Voltage 12V Trigger Bypass
Benchmark Bi-Directional 12 Volt Trigger - Technical Details - Benchmark Media Systems
Project 156
Amazon.com: BobWire DAT1 Adds a 12V Trigger! Compatible with SONOS Connect, Echo Link, ChromeCast Audio, TV, Anything with an Optical Audio Out. Auto Power On Amplifiers & Fans. NOT Compatible with AV
Amazon.com: BobWire DAT1 Adds a 12V Trigger! Compatible with SONOS Connect, Echo Link, ChromeCast Audio, TV, Anything with an Optical Audio Out. Auto Power On Amplifiers & Fans. NOT Compatible with AV