Your amp is quasi-complementary output. To make it full-complimentary, you'd need to remove the entire point to point wired back wall and sockets, and build a new one from a schematic. Bad idea, as Joe has engineered a complementary output back wall circuit board, one for each channel. Very rugged and well engineered. And not that hard to do if you can solder, follow instructions, and are mechanically inclined.
Sniff is correct.
Sniff is correct.