I'm ordering a Sennheiser Evolution Wireless vocal system and have three choices in frequency ranges. This will be my first of a few wireless systems I will get over the next few years. How do I know which range to choose from for Canada? A range (516-558 MHz), B range (626-668 MHz) and G range (566-608 MHz). Am I correct that all these ranges would work and it is when you are in and above the 700 range this is more a concern?