Originally Posted by TooPoor
Good stuff! I can't believe I didn't notice that about the 1100... 4000 does look like a good option.
The Denon AVR-X4000 has the improved version of Audyssey room equalization called XT32 which will provide a significant sound improvement over the lower versions. This alone is worth the up-grade price.
The power output of the X4000 in 2-channel stereo mode is 125W per channel at 0.08% THD into 8 ohms. The KEF LS50 has a maximum continuous rating of 100W into a nominal impedance of 8 ohms - so from a power output stand point, the X4000 and LS50 will work together.
Speaker power requirements are exponential. How loud you want to play the LS50 is very dependent on your room dimensions, where the speakers are placed in the room and where you sit (i.e. the distance between you and the speakers). How loud you play also determines speaker power requirements. Most people will perceive a change in Sound Pressure Level (SPL) of 3dB. This 3dB change will require 2x more power than before.
To play 2x as loud requires a 10dB change in SPL. A 10dB increase in SPL increases the power demand by a factor of 100x.
Maranatz NR1504, Oppo BPD-93, MTV 7000D, LG LW6500, aTV, WDTV Live, Harmony 650 remote, KEF E301, MiniDSP(2x4), Rythmik F12G