I have now used this a couple of times and it works extremely well, but yes, you need both the CSM1 and the CBCSM1 together (remember that you'll have to purchase the power supply for the CBCSM1 as well).

You'll plug your Vizio plasma into the CSM1 current sensor, then run the current sensor to the CBCSM1. Then you'll connect the Nevo Voltage sensor to the "GND" and "Pull Up" connections on the CBCSM1.

Enjoy and remember to program your If/Then statements.