Why does my 35 watt tube amp draw 300 watts of power

Tube amps are only 5% efficient.

We can easily see from the opening post of this thread that the above statement is false. If you can get two channels of 35 watts from 300 watts of wall power, clearly the amp must be more like 20% efficient, in this case 23.33% efficient, which falls within the norm for many tube amps.