If you post a picture, someone can probably ID it for you and get within a few years of it's age. From what you've posted, it's from sometime between 1965 and 2002, is either tube or transistor, and is between 40 and 300 watts.
Seriously though, put up a pic and you should be able to get a good idea of it's history, specs, etc.
If it says "Sunn Electronics Inc." with no model name, it's
probably pretty old.