Component recommendations: best bang for buck.

My own preferences are probably different from yours.  I care mainly about sound quality.  I do not care about 4K.  I do not care about Dolby Atmos / DTS:X.  I do not care about room correction (I did not like Dirac room correction when I tested it).  After testing several HT Processors,  I went with a Krell S1200U 3D, which was the best quality sound for my tastes.  As I said, the power supply is somewhat undersized at 13,200uf for the analog section (4 x 3300uf).  I soldered in another 2 x 15,000uf to these sections.  This gave me much more fully and powerful bass, fuller midrange and less brightness/leanness.  The Krell Foundation may not have this problem because it only uses op amps.  The discrete Class A analog circuits of the S1200 are very demanding on the power supply current.

The Krell Foundation would be missing these features compared to the Marantz 8802a.  They are what I call "bells and whistles" features:

- 11.1 channels output (Krell only has 7.1 channels)

- Dolby Atmos surround decoding (not required for 5.1 channels)

- DTS:X surround decoding (not required for 5.1 channels)

- Auro-3D decoding upgrade

- Bluetooth and wireless networking, for DLNA and streaming audio, including Apple Airplay, internet radio, Spotify, Pandora, SiriusXM.

- 4K video processing and upscaling (Krell just passes through video)

For my own personal preferences, I like the high resolution, high detailed, high impact sound for both music and home theater, so I would be choosing the Krell Foundation for myself if I was in your shoes.  I think that MC303 is an awesome choice for your future and I think it would match well with the Krell Foundation.  For the surround channels, it looks like there is a McIntosh MC152 on audiogon for $3k.  I understand if you didn't want to spend this much right now for surround amp.  You don't have to.  For example, you could throw in something like a low cost Parasound A23 for around $650 for now.

There are other people who like a very laid back warm sound (they don't like the "in your face" detail and impact of the Krell sound).  In these situations, the Marantz 8802a would be a better choice for them.  It's all about personal preference.

On the AV Receive discussion.  You could go ahead and get a Marantz SR7012 AV receiver for about $2k or an Anthem MRX 720 for $2500.  This would save you money in the end because you would only need to get an external 2-channel preamp+amplifier or integrated amplifier for your music.  The 40% of your home theater listening would not be as good.  It depends on how much you really want to invest.

Oh, I just saw you changed your post.  The original post said you were about to bid on the MC303.

I can only theorize on what the sound of the Krell 7200 vs MC303 is going to be.

Based on what I have read and what I know about Krell, the Krell 7200 is --probably-- going to be a lot more detailed and fast when compared to the MC303.

The MC303 is going to have a lot more brute force which means stronger bass and midbass -- as well as fuller midrange.  It will probably be more laid back than the Krell, but as I have not heard either amp I cannot be sure.

It would actually be a hard choice for me.  It's strange, but I might actually lean towards the MC303 because of the size of the power supply and the overall capability of the amp.  The Krell actually runs out of power and can't drive all channels at 200 watts.  You only get about 150 watts with all channels driven.

I currently use the Emotiva XPR-1 monoblock amplifiers for my front three channels. If I had to look at upgrading, I would be going after the Parasound JC1 monoblocks for left/center/right.  Maybe a Parasound A21 for the surround channels.

Since you are ultimately wanting to get Martin Logon electrostatic speakers, I would probably look at a higher power amplifier.  The MC303 is a good "future" choice if you are after that sonic signature.  The Parasound JC1 would be different.  I think it would have a lot more detail and slam and punch when compared to the MC303.  I'm sure the MC303 will sound beautiful though.  It might still be a better match to a Krell Foundation and the Martin Logans.