Hi, I think that you don't need an HT processor at all, since you already have it in your Marantz. All you need is a high quality analog-only preamp. I could give you a few options: McCormack MAP-1; Bel Canto Pre6; McIntosh C-45; Meitner Switchman; etc. That way your needs for a good quality music playback will be served without sacrificing any performance which, I believe, is inevitable using almost any Pre-Pro in the same chassis with your analog preamplification.
And, of course, you'll need some additional channels of amplification.
I switched from Bryston SP-1.7 Pre-Pro (which considered to have one of the best analog bypasses among various Pre-Pros) to McIntosh C-45 multichannel preamp with substantial gain in music playback quality, without any sacrifice in HT performance. Again, this is my system and YMMV. Regards.
And, of course, you'll need some additional channels of amplification.
I switched from Bryston SP-1.7 Pre-Pro (which considered to have one of the best analog bypasses among various Pre-Pros) to McIntosh C-45 multichannel preamp with substantial gain in music playback quality, without any sacrifice in HT performance. Again, this is my system and YMMV. Regards.