The receiver is a combination of several units.....generally a radio tuner (or in modern gear internet apps/access), and pre-amp, and amp. Most speakers are what we call passive, i.e. require separate amplification. There are active speakers with specifically provided amplification/crossover but not often used in whole home type audio setups as you appear to have. Did you get rid of the old receiver? Whole home speaker setups aren't always the best to use a receiver with either, would need details of your speakers and those controllers....