Most of us are building for ourselves and not marketing products so many
common amp specs are not that important. However, I'm interested in how
power is calculated and would like to see some RAT feedback on this
subject.

There are two power calculations:
P=V^2/R (call this 'voltage power')
P=I^2*R (call this 'current power')

Let's take an example of a constant-current Class A output stage:

Load = 4 ohms
Peak-to-Peak (P-P) output voltage before clipping is 8 volts.
Using the voltage power formula:
(8*8)/4=16 watts

However, it's customary to represent voltage with the root mean square
(RMS) value. So 8 P-P becomes 5.66v rms when divided by 1.414 (sq. root
of 2). Now, (5.66*5.66)/4=8 watts

The constant current of the primary is 100ma. The output transformer
has a winding ratio of 35:1 so this calculates to 3.5a at the secondary.

Using the current power calculation:
(3.5*3.5)*4= 49 watts

Q1:Would it make sense to calculate the current power using a reduced RMS
value? So 3.5/1.414=2.48a. Using this value:
(2.48*2.48)*4=25 watts

Q2: In the end, I imagine that the amp power would be described using the
_lower_ of the two calculations. I would say that this is an 8 watt
amp.

Comments?