Amp draw, Class A vs AB, oh my?

I had to do some repair on my KSA50 today. I thought the Thermistor had failed but it just turned out to be a loose screw on the patch panel. As I was buttoning it up I noticed my WattsUp meter sitting on the table so I thought I would hook it up and see what the Krell was drawing. Oh my, at 123V AC it was drawing 3.4A. this got me wondering so I hooked up my Symasym. It draws 0.42A. My three channel ESP P101 only draws 0.64A. Does this seem right? I had no idea that Class A amps were so inefficient.

Thanks, Terry