The X4000 is a 7.2 receiver and comes equipped with Audyssey MultEQ XT32, Audyssey Sub EQ HT & Audyssey LFC as well as useful features such at 7 HDMI inputs, 3 HDMI outputs with multi-zone...
XT32!, Sub EQ HT, easy setup, plenty of power, detailed on-screen menus
remote is not backlit, crossover uses 20Hz increments, no built-in wireless
The X4000 is a 7.2 receiver and comes equipped with Audyssey MultEQ XT32, Audyssey Sub EQ HT & Audyssey LFC as well as useful features such at 7 HDMI inputs, 3 HDMI outputs with multi-zone capability and great networking tools like Apple Airplay. It also includes built-in apps such as Pandora, Spotify and Sirrius/XM radio.
I upgraded to the Denon X4000 from an Onkyo TX-NR 709 with Audyssey MultEQ XT and the difference in sound clarity, quality and detail is amazing! This is hands down the best AVR upgrade I've made yet.
My subwoofer has come to life! The detail and nuances in the bass are extremely impressive. Watching Pacific Rim on the Onkyo, the bass from my sub was a steady 1 or 2 note boom, boom, boom where the Denon is giving me subtle details instead. I attribute these differences to the X4000's Audyssey XT32 and it's extra high resolution filters.
The menu system on the Denon is straight forward for the most part. You do have to do some doubling back between the different audio/audyssey menus to get everything tweaked the way you like it but I think I was able to get it all done in about 15 minutes (after running the Audyssey room measurement sequence). As of the most recent firmware update, I've found that the input format auto-detect no longer works... the X4000 will remember the last sound mode selected for each source. I have mixed feelings regarding this change.
So far, my only complaints are the lack of a backlit remote on a receiver that cost $1300 and I wish the crossover allowed for finer control... my Onkyo allowed me to select 10Hz filter increments where the X4000 only allows it in 20Hz increments. Not the end of the world but it was a bit dissapointing.
Overall, this is a fantastic product for the money and hands down it's been the single most impactful upgrade to my home theater sound system. If you are looking for an AVR in the $1000 range, I would highly recommend looking at the Denon X4000.