Power consumption

[thumb5]

Off               -    8.8w
Standby       -   10.8w
-34dB USB   -   31w
-17dB USB   -   37w    temps 41, 39, 44

I'm still surprised. 
So few watts create so much heat.

The temperatures in the amplifier depend on how much waste energy in the form of heat the amplifier is having to get rid of, and how efficiently it can dissipate it.  The more efficiently the amplifier can convect, conduct or radiate heat to it surroundings, the lower the temperature rise above ambient will be.

For a bit of contrast, think how hot the element in a traditional 40 W incandescent bulb gets - that's dissipating about the same amount of heat but very much less efficiently (by design).

The modest temperature rise is the price we pay for having a relatively small, shiny box rather than a large matt black one with huge heatsinks (or water cooling, or some other exotic method for getting rid of the waste heat). Fortunately the Devialet is quite an efficient amplifier so it generates a fairly small amount of waste heat compared to others (e.g. class A, class A/B) with the same power output to the speakers.

Why do we need power cords thicker than our thumbs to deliver what amounts to a very modest current ?

The simple answer is that we don't.  At least, not for any technical reason.