A/V Processor and Amp for B&W speakers?

Ok, in doing a lot of digging around and looking at second hand prices I included Yamaha CX-5100 & 5200 in my searching (based on some other Audiogon threads) and stumbled upon a CX-A5000 for $550 (just over $600 including shipping), after looking at reviews and forum comments I pulled the trigger. Seems like a decent price to me, it doesn’t come with a setup microphone though so I need to find the right one as it seems there’s a few different versions out there. I’ll contact Yamaha but any advice on this and setup welcomed.

That's a really good price for the A5000, if it's in good condition.  Since it's missing the microphone, it's likely missing several other pieces.  Dod you get a remote control with it? 

The Yamaha is likely not going to have bass/midbass that is as full sounding as the Marantz.  However, it is going to have better high frequency resolution.  It could come across a little bright/harsh, especially if you pair it with the Monoprice Monolith amp and your B&W speakers.  You'll have to let us know how it works out.  There are ways to help calm down the Yamaha if your sound is too bright/harsh (i.e. fuse upgrade and power cord).

It does come with a remote and power cord, and visually in the add it “looks” in good condition, but I bought a squaretrade protection plan for some additional comfort in case it’s a lemon.

In terms of bright sound, interesting point, but at least the Yamaha / Monolith combo should be less bright than my current amp, which is Pioneer, a brand known for being on the bright side generally I believe. There again I’ve never had separates before so this is new territory for me.

Circling back to this thread for an update.

Firstly I installed the CX-A5000 as the pre-amp / processor and used my existing SC-27 as the amp as an interim until purchasing an amp. I honestly didn’t expect this step to yield much sound improvement but was really surprised, my system came alive and it made me realize how thin sounding it was using the SC-27 alone.

After deciding to get a Monolith amp I price watched for a few months but it became clear these things never go on sale nor was there any open box / refurbs available, so I went online to buy one and they were then out of stock for over 2 months, ugh, anyway a 7X arrived this week! Even without any break in or setup this has brought another big step change in sound quality, much deeper base, tighter sound, more clarity, and such a distinct separation of each instrument and vocals, such an engaging sound, couldn’t be happier so thanks for the advice!

The final step is now the setup but I’m still waiting for the setup microphone for the CX-A5000 to arrive. In the meantime if anybody has any advice on setting up these Yamaha pre-amp / processors I’d appreciate it. Is the YPAO auto setup a good starting point?

That's great!  I'm glad the Monolith worked out!  I think it's a much better option than the current Emotiva "Gen 3" amps. 

As far as YPAO, I personally don't like automated room correction systems.  I'd rather manually EQ something if I need and then use room treatments (acoustic panels) for the rest.