The big difference between the two new receivers is that the AVR-693 is a 6.1 channel model, delivering 6 x 120w (6 ohms) while the AVR-793 is a 7.1 channel device, delivering 7 x 135w (6 ohms). That said there are plenty of common themes...
Massive toroidal transformers and high-grade capacitors The AVR-693 and AVR-793 feature overspecified toroidal transformers and high-grade capacitors (AVR-693: 40,000 µF, AVR-793: 60,000 µF), for extra stability and large reserves of power.