The Yamaha R-N803; with it you also get preamp functionality, a streamer, and internet radio. It is slightly cheaper, and rates higher on the SINAD graph. I have it and I am happy with it.
Yes, the Yamaha sounds great. On paper. Until you listen to it. I have the Yamaha R-S700. The power section (amplifier) is not bad but the pre-amp is awful. I don't believe on your model you can separate power amp and pre-amp. I've added a pair of Pro-Ject Amp Box DS2 Stereo recently to replace the Yamaha R-S700 amplifier section (stopped using the pre-amp a long time ago) in my setup. The Pro-Ject Amp Box DS2 use the UcD102 from the same Hypex UcD series as this NAD C268 (Amp Box Mono uses the UcD180LP). The Yamaha R-S700 power section bi-amped on the AB speaker outs sounded quite fine (a touch better than my vintage NAD C320BEE for instance) until I switched in the Amp Boxes. Suddenly guitars squealed, bass thumped and orchestras filled the whole room, with the ability to place the instruments. Music from the R-S700 in comparison was a confusing soft blur.
It's not a question of volume/watts. I'm not a very high volume listener, except when testing or not sitting working, my speakers are only a few metres away when working.
Of course, I'd rather have two x stereo Purifi amps and I'll probably get there in a few years when the prices sink a bit and after I upgrade my speakers first. Stepping up to My NAD C372 amp section is dead. I remember the NAD C372 as as wonderful as the Pro-Ject's amp boxes (moving to the Yamaha six years ago was a clear step down) but of course can't A-B test the two. The NAD C372 pre-amp is also in a different class, competitive with the NAD C165BEE dedicated pre-amp which apparently rivals most $3K pre-amps (I don't have a $3K pre-amp so this is hearsay).
In any case, there's a lot of good press around here on the Yamaha A-S and R-S series. I'd seriously suggest auditioning them head to head against affordable Class D Hypex amplifiers before leaping. Even a DAC straight into a well put together UcD series amp (let alone an NCORE) will blow the socks off these Yamahas. One good word for the Yamaha amps – they are reliable and the noise floor at idle and full volume is basically silent. There's no line noise at all. Quite impressive.