Summary: Couldn't be happier with this AVR. I have the Energy Take Classic 5-pack and Energy EW-100 sub for speakers, and they have come alive with the NR-1403. Audyssey setup was very good with only a minor crossover tweak needed for my surround speakers. As others have said the sound is on the rich, mellow sound and the soundstage feels all enveloping. I haven't been able to "max" out the volume, because it would be ear splittingly loud. PLENTY OF POWER for my 20x12 room.
Summary: Very impressed! Awesome receiver. First time with Marantz. Bought this receiver as a replacement of an Onkyo to hook up with my Mirage speakers + Polk Pro Sub. I can say the Marantz performs way, way better than the Onkyo. Marantz has an expectacular sound clarity + richness. Every detail is present, and it is able to match perfectly satelites with sub. Even the image seems a lot sharper. Setup is very easy and menus are very intuitive.
Summary: I purchased this for a mid-size home theater room. Don't the the 50watt rating scare you away from buying this unit. It has plenty of power for what we need and has great sound in a 5.1 system. If you're looking for a receiver without all the frills of internet, airplay, etc. (which we were since we have that capability with other components in the system, this is a low priced great way to go.
Summary: Probably a bit early for me to be reviewing this since I just got it yesterday. But here goes anyways. I bought this because I thought my Yamaha RXV667 receiver had a bad input which was causing my sub to produce low sound. Turns out it was the sub, not the receiver. I really should just return this, but I'm keeping it, and there is nothing you can do about it. The Yamaha is 90 watts per channel (vs. 50 on this), 7.2 with zone 2 and 5.1 preout.