There is a basic problem with using Speaker B for the other room. If you EVER put the main room into surround, you will need to not only switch speaker B on, but also put the receiver back to two-channel stereo, to use Speaker B. Otherwise, you will get very little audio, with no center, in Room B. This usually is cumbersome enough that nobody wants to deal with it.

The next level of cumbersome comes when you actually put volume controls on the outputs of Speaker A and Speaker B so that you can, for instance, have Room B on full with Room A on at a low volume. Of course this is possible, but then you have to ALWAYS turn Speaker A's volume control all the way up when you go into surround; otherwise Room A's left and rights will be lower than they should be and your surround volumes will be all out of balance. Again, nobody I ever mention this to wants to deal with it.

But it is easy to set up. Just not easy to use.