I have an outdated Sherwood RX 4109 receiver. I have two speakers wired in right now. They are each Definitive 800 Bookshelve speakers. The Sherwood receiver has been passed down to me so I don't have much info on it, but I keep reading that if you use the A and B speaker function at the same time you must use 16 ohm speakers. At the moment my two speakers are plugged into A only. But, I was looking to use both A and B soon, because I was interested in hooking up a sub or maybe some more speakers. So, at the risk of sounding stupid, is this a cumulative ohm or should each speaker have to be 16 ohm? I can't find the manual for the definitives or find the ohms of them online, but I have a multimeter I was gonna test on them (perhaps someone knows off hand). They say this could really make your receiver shit the bed and it was a hand me down that I was really lucky with, don't want to have to wake up one day to find out I gotta go get a new one just cus the speakers ohms were over working it. Thanks to anyone who can help.