Welcome to the site.
Your receiver is most likely 30 watts per channel, and not meant to drive more than one set of speakers at a time. The seller/post on ebay is completely misleading, stating a very light 17lb receiver is very powerful, and also stating power output per channel of 125 watts, is actually the power consumption! Two different animals. Since the unit is probably 20 years old, it most likely has some lose solder points. It's hanging on by a thread right now. You can see the street value by the ebay post, so use it until it completely dies, and upgrade to a better unit when the budget permits.