2 or 4 channels?

I have an old sony tan 80 es, it has two speaker binding post in the back (A and B ), there is also a swtich in the front to select speaker A or A + B. Would it work as a 4 channels amplifier if I use both binding post and select the A +B ?
No. It is a two channel amp: Both right speakers (A+B) and both left speakers (A+B) carry the same information.
and you would not want to listen to it with 4 speakers any how!even if all 4 were the same!!!