Thank you all so much for your responses... I got an extension cord and powered up but there's definitely an issue.  As soon as it's powered on it has a hum that alternates loud every second like a square wave. None of the knobs or switches have any effect on the noise and no input is heard.  Any ideas on what could cause this? 

I just acquired this vintage amp and I'm trying to see if anyone might know anything about it...  It has a model number DV112 etched into it.

I'm also trying to find a suitable power cord to use with it... It's a three prong ac connector.  Would any extension cord work?  Anyone seen anything similar? This is my first vintage amp so any help would be amazing!