Just upgraded from the 4310ci to the 4520ci, and boy what an adventure it was. First thing I noticed was the weight, they nearly weighed the same, after removing the 4310ic and installing the 4520ci and running the audyssey calibration I was VERY disappointed by what I was hearing. Here is where the adventure began, because I know that this unit should sound better than my old one. My setup: 7.2 Mirage Speakers with 2 Prestige s10 subs, what the 4520ci MultEQ XT 32 did to my subwoofer levels was laughable, -9 -10?! I knew something was odd when during the setup it asked to level EACH sub at 75db, solution, I used the y adapter and manually leveled both subs to 75db and switched back and forth from the y adapter to the dual outputs until each sub calibrated out to the same level witch ended up being -5/-5. After all of that I was still highly disappointed with the sound, the 4520ci MultEQ XT 32 calibration's midrange response was VERY thin! It was like I was using 7 satellite speakers and the bass was still too low.
Now I am very upset, and started thinking how can I get this receiver to sound like my old one, then I had an epiphany, use the 4310ci as a baseline for the 4520ci. The most important variable in the calibration was the microphones, the old mic (DM-A409) proved to be more sensitive, by about 2db. After recalibrating with the old mic, voilà, pristine sound, oh then I adjusted each sub by the +2db difference then added 1 more db for effect (-2db each sub) and I was in heaven! The accuracy is unparalleled, I have to towers on the floor and my center is 5ft off the ground and the L-C-R sweeping effect is seamless, actually all channels are! Be sure to adjust your crossovers to your liking and use LFE+Main if your fronts don't produce enough bass for you.
The dtsHD-MA track on the Dark Knight Rises is EPIC, the Batman police chase scene, EPIC, when Bruce Wayne climbs out of the pit, EPIC, the last 30 seconds of the movie and the end credits, SUPER EPIC SOUND! This is where you need the midrange response to be good, to produce that big screen sound. Yes, MultEQ XT 32 subEQ is worth it, it doesn't kill the subsonic lows like it did in the past and with 2 subs equalized, aw man!
Now on to the pros and cons, CONS: Remote, no (native) dts 5.1 while in 7.1/2 speaker configuration, no auto sound format decoding, example if a source has a SB Flag (EX) you have to manually switch to Dolby EX, no one button speaker level adjustment, microphone, slight electrical buzz, and weight. Lack of over all options, too many to list. Pros: Clean, strong sound, fast menus, subEQ, inCommand, assignable amps are very nice, I love using my tablet as a remote, fast audyssey calibration, instaPreview.
Overall I am impressed, although initially I was disappointed, I still feel they should not have over simplified the options, like, the option to disable the audyssey L/R bypass, multichannel in sub level adjustment, no adjustments can be made during pure direct mode, surround back auto decoding, no fast one button speaker level adjustment, even the 2ch mode options are greyed out, haven't figured that one out yet.
P.S. I do also miss having both audio source input diagram on one side and output on the other, now you have to choose one or the other.