Hi Sean,
You need audio wattmeters which generally take the form of VU (volume unit) meters which have ballistics suitable for riding the peaks of an audio signal. These read in dB which is logarithmically related to the power in Watts. So you would need an attenuator switch that would yield 0 dB = 200 W, 20 W, 2 W, 0.2 W, etc. You should be able to find a pair of nice old VU meters on ebay from old recording studio equipment, tape recorders, etc. If you tried to use a 200 W linear audio wattmeter, you would hardly ever see the needle move because of the logarithmic response of the ear to power (i.e. your average power will be a few Watts at most).
Regards,
Lloyd