you can connect 4 speakers to A30/A50, but need to make sure the impedance is more than 4 Ohm. eg: connect 2 8Ohm speakers in parallel to one channel, or connect 2 4Ohm speakers in serial to one channel.
And for one AMP, it can’t play different music to 2 zones, need to place one AMP for one zone.
Btw, when you group for multiroom, it will bring a significant delay on the sound out. Not suitable for TV.