Home Theater Receiver recommendations for B&W 803S?

You two are making a pretty compelling case for the Rotel!  

However I just took a measuring tape to my cabinet, and I don't think I can actually get it to fit along with my Denon (or the Marantz). The Rotel is really huge... The Monolith is about 2" shorter. So that may win the argument.

Then again, it may be time to go rack shopping...  Rabbit hole, indeed...

Agreed. Emotiva is great for the money but Rotel & NAD alikes are better but cost a little more than the Emotiva. Rotel still offers great value considering their modest asking prices but are not on the same level as real high end or higher priced Krell, Pass, Hegel, Classe, Audio Research, McIntosh, Naim, Linn, Vitus Audio, and the list goes on and on and on

Welp, you guys won me over. Just pulled the trigger on the Rotel. :)

(now to figure out where the heck I'm actually going to put this beast!)

@awilder

Congrats on the purchase! I think you made the right choice. Since the RMB-1585 is huge and very heavy I suggest you put it on an amplifier stand on the floor. The Rotel RMB-1585 never runs hot no matter how hard you drive it. It stays cool the whole time.

You will be happy with its performance has plenty of muscle and unlimited power reserve to drive just about any speakers and it will sound good on your B&W 803S. The noise floor is surprisingly very quiet especially for the price.
This amp is much better than your Denon receiver’s internal power amplifiers or any receiver’s internal amplifiers.

Now you just need to purchase good quality analog interconnects to connect from your Denon receiver’s preamp outputs to the inputs on the Rotel RMB-1585 amp. Do not skimp on cables. I would suggest that you also upgrade the power cord. The stock power cord wouldn't do a good job.

Later down the road you can sell the Denon receiver and get a good quality AV preamp surround processor (pre pro). The recently discontinued Marantz AV8802 and the discontinued Classe Sigma SSP version 1 will be a great choice. But the Classe Sigma SSP version 1 (not Mk2) does not support 4k video, Dolby Atmos, DTS-X & other latest formats & codecs so it can be had for around $2500 to $3k range in used markets. The Classe Sigma SSP Mk2 supports 4k, hdcp 2.2, Dolby Atmos but you will probably end up paying more or even full price $6k since it support The latest formats. The Marantz AV8802 supports 4k hdcp 2.2, Dolby Atmos, DTS-X, Auro 3D and can be had for around $2k to $2500 in used markets since it's recently been discontinued. 

IMO the Classe Sigma SSP will pair better with the Rotel RMB-1585 amp cause the Rotel RMB-1585 is warm with smooth highs and isn't the last word in resolution, inner details, nuances and transparency. The Classe Sigma SSP is very transparent, excels in detail retrieval, nuances and resolution. The Sigma SSP sounded very resolved, fast and clean. So it will compliment the Rotel RMB-1585 warmth liquid and fluid sound. The Marantz AV8802 however is somewhat warm and the details, transparency, nuances aren't as good as the Classe Sigma SSP. Therefore, the Classe Sigma SSP will pair better with the Rotel RMB-1585 amp. 

Let us know of what you think of the Rotel RMB-1585 amp once you receive it. 

I have the Rotel rc and rb 1590. 👍. Check out Darwin cables.