Emailed Oppo, here is what they said.
It is always active. You need to use a 3.5 mm mono plug to go from the Trigger Out to the Trigger In of your amplifier. It’s a 12 V output.
Judging from the MC152 user manual, it looks like you’re referring to the “Power Control” section on the back. This appears to be a proprietary system similar to a 12 V trigger, but the McIntosh user manual suggests that it may only work with other McIntosh components.
So what do you guys think, is there a mono to stereo jack cable, or like I feared , its a Mac only thing.