Let's get to first principles:

I keep an 11-tube tuner that draws about 60 watts and is fused with a 3/4A dual-element fuse.

Matching to it is a 35 watt (2 x 17.5) 6-tube power-amp that is fused at 1.5A. It is a Class A/B device.

Yes, the part that moves the air takes most of the power.

Now - digital radios are all/nothing devices. The term is 'cliff effect', there is no fading, it just drops off the cliff. The power-amp part is probably a Class D device. Meaning it only draws power when it is passing signal making it about 90% efficient.

So, at no-signal conditions, the radio section is still drawing 100% of its necessary power, the amp is drawing (very nearly almost) nothing. But, if you are making your ears bleed, the amp section will be drawing much more than the radio section. Phil's piece of string is an apt analogy.

Peter Wieck
Melrose Park, PA

Broadcast and reception take a lot of power if youre planning that through an MP3 but, yuck !! Re-using earbuds off of the floor, ewww!!