SWTP 207/A help

So I just got this amp from my friend, who said volume knob didn't work, just played at max volume. I set it up, nothing but a rather large humming (coming out of speakers), and a burning smell. Any thoughts?
I thinking the no sound is from the volume knob being down, but I was a bit concerned by the humming, and a lot concerned by the smell.
Also, whats with the inputs (this is a mono amp) labled AC and DC?
Any ideas on which I'm supposed to plug into?

 

I googled SWTP 207/A. Looks like it was also known as "Tiger .01". It was sold as a kit or assembled.
SWTPC Tiger .01 207A Schematic and Parts List

One guy says to use the DC input as the Line In. I didn't see any mention of the AC input.

I read 4 different mentions of them "blowing up" and 3 of them catching on fire. (I didn't spend a lot of time researching this but it seems kind of scary to me.)

 

hmm... Don't really want that to happen... I might just harvest some of the parts from it for other stuff.