So, after watching a few Blu-rays this weekend I'm now even more impressed with this AVR's performance.
I started yesterday with two concerts. Mumford & Sons: Road to Red Rocks and Sully Erna's Avalon. Both have simply stunning audio and the 4520 produced a very immersive sound stage. The clarity of the audience in the surround speakers was wonderful, as was the detail of the instruments and vocals in the main and center channels. I invited a good friend over to watch both concerts. He's a musician and has an incredible ear for sound--much better than mine. When I first set-up my Anthem MRX-700, he was very impressed by that AVR's sound over my 3808--and so was I. This time I decided not to tell him that I'd replaced my MRX with the 4520. I made sure that I was already watching Mumford & Sons when he arrived so he couldn't see the new Denon sitting in my AV cabinet at the back of my home theater. After the concert I asked him his opinion of the sound and he said it was just a good as he remembered it the first time he'd hear my new AVR. Detailed, clear, enjoyable. Needless to say he was floored when I told him I'd just replaced the Anthem with the 4520 due to an issue that meant me having to ship off the MRX for service. I loved the sound of the MRX, it was much better than my 3808, and I was worried about giving that up for a more feature-packed and, hopefully, much more reliable AVR. Thankfully I found the 4520 to have wonderful sound at least as good as the Anthem's, but now with someone I trust agreeing with me, I feel vindicated with my decision to go with another Denon. No placebo effect here.
Today I watched the blu-ray if John Rambo. From the amazing jungle sounds to the thumping of the 50 caliber machine turret unleashing hell on the enemy, the sound was phenomenal, powerful and detailed. Now more than ever I'm convinced that Audyssey did a much better job with room correction for my subwoofer than ARC did. The bass is powerful and detailed, but not too loud. Just right for my taste.
So, after 4 days with the 4520 I'm sold. It's an amazing AVR that I'd recommend to anyone wanting a beautiful sounding and looking heart to their home theater.