I know I'm a few years too late here, but if you are anything like me, once you get a piece of gear, it stays. I recently got the same amp you asked about. Like you, I couldn't find anything about it online. After far too long on the internet looking for info I figured out the company that bought Millenium some years ago, who are now located in Texas. They're called Atlas, and still deal in the audio world.
The support guy I was connected to had no idea what I was talking about, but knew that an older employee had been with the company a long time might know something about the unit. He also said that I was lucky because the older dude was retiring in 2 weeks. Anyway, long story longer, those guys dug into the depths of their basement and were able to locate the sales flyer which included the amp specs. I couldn't believe they cared that much. But they did and took time to help and are awesome. Here's a link to the flyer: https://acrobat.adobe.com/link/track?uri=urn:aaid:scds:US:e9c55a9e-38c1-3d0b-bca5-b4beea2f19ac