Thanks everyone. I checked all over. No markings whatsoever. That’s why I only sent the one pic.
I’ll be honest. I don’t know what I’m really doing with audio equipment. Apologies.
What wire(s) would I need to test it with my phone? I turned it on and no music. The only ports on it are that white circle one and green rectangle one on the front. I woulda guessed a red/white av wire but there’s only a white circle port
It is pretty clear that it is a mono PA amp. The two pin connector on the right would be for the power supply. None of us will have a clue what voltage it needs to run it.
The round RCA connection is for a mono source input.
So this will not work, without a power supply and a mono music source. If you don't know what you are doing this is useless to you. Absent information left about it, or someone experience taking a look at it, you will not get this working.
You would have to have it on a test bench and fire it up from a Variac unit, with a test tone on the input. Then you would need to monitor the output on an O-scope, and gently increased voltage until you had a decent wave form.
So only someone very experienced with test gear will determine how to use this unit.
I can find no Muzak amp that looks anything like that.
So what you have is a DIY amp, most likely made from parts or some type of kit.
We can't help you any further I'm afraid.