The powerful 7-channel amplifier section features identical power amp design on all channels along with high current discrete power output devices. Rated at 105 watts per channel (8 ohms, 20 Hz~20 kHz, .08% THD), the AVR-X3100W is also rated to drive lower impedance speakers, down to 4 ohms. Our new Eco amplifier mode automatically adjusts power output based on volume level, and an on-screen Eco meter lets you see the power consumption savings in real time.
Isn't that the one and only function of the volume control?
This is from Newegg.