Is Marantz AV8805 good enough pre amp for McIntosh MC8207

For your stereo listening you can get a high end very good stereo integrated amp. Doesn't have to be stereo separates. Really good stereo integrated amp such as the Gryphon Diablo analog integrated amp (expensive) but you will need a very good front end source components to go with that. There are other countless options out there. 
Do you have a turntable? If you only had a digital front end source components you should consider getting either a PS Audio DirectStream DAC with a very good streamer and transport, various Naim DS, either Linn Akurate or Klimax DS, etc.
Again there are countless other options out there. 

If I were you I would get the Marantz AV8805 over the Mac MX122. If you want to go with Mac I suggest you look at the MX160 as this will be a step up sonically than the AV8805 or the MX122. However, the Marantz & the Mac MX122 are very good for HT but aren’t good enough for 2ch music playbacks IMO.
The MX160 might be good enough for your 2ch listening needs depending on your expectation when it comes to stereo listening to music. Another processors that will perform well in 2ch will be the Classe SSP 800 & Classe Sigma SSP, Krell Evo 707, 1200U and possibly the Krell Foundation series, Cary Cinema 12, Bryston SP4/SP3, Meridian Reference 861 v8.

The Mac MX122 was based on the Marantz AV8802. They only shared same base platform, HDMI boards, GUI, OSD & firmware as well as remote. But Mac built its own power supplies, DAC, clock, digitall and analog audio circuitry, analog audio output stages, voltage regulator, etc.

If 2ch is important to you I suggest you look at a high end stereo preamp with HT bypass feature. But you should also get a good dedicated stereo or monoblock power amps for your front 2ch speakers if 2ch listening is of important to you.
While your Mac MC8207 seven-channel amp is fine for HT but it isn’t good enough for 2ch listening to music.

Sorry cause first I didn't know what your speakers were. My bad. Yes, what you currently have are more than good enough for your B&W 683 S2. I think the Mac is somewhat overkill for your speakers. The Rotel amp will do just fine for your 683 S2. 

@tomiiv30 

For your B&W 683 S2 speakers you can use your Marantz AV8805 and your Mac MC8207 seven-channel amp for both stereo and HT imo until you upgrade your front speakers for stereo listening, then you can start looking for a dedicated stereo preamp with HT bypass feature and a better stereo or monoblock amps for your front speakers. But until then you are good with what you have.

Yes you definitely need to upgrade your speakers from the B&W 683 S2, especially now that you have the Mac C52/MC462 combo for your stereo listening to music. You can move up B&W line such as the 803 D3 or the 802 D3 and they will sound very good paired with the Mac MC462 amp. And you will need to get a matching center channel speaker for them, which is the B&W HTML1 D3 center speaker. For surrounds you can get the B&W 805 D3 unless if you're using those in-wall surround speakers right now. 
Then you will be all set. 

Congrats on the purchases.