You may see an improvement over what you have with the Marantz, but I doubt it is going to measure up to the B&K sound even with the MultEq.
It's always been a problem that the higher end lines lag the consumer grade gear in the latest connectivity, processing and features. There is usually a delay in the release of the technology or use of (licensing). They try to gauge what will be popular and keep the gear a bit less cluttered instead of loading it up with everything. Meridian would be a high end exception, because they are engineering their own products/processing to license. Their 800 series card based architecture was an attempt to future proof a piece of gear. Very expensive equipment though.
A baby step might be the new Anthem Receivers. Not sure who they are outsourcing, but it looks a bit like Pioneer from the back. They are dropping some features like S-video, so they can up the quality in other areas. Anthem Processors might also be worth a look used. They did offer some upgrade paths for future formats, so you may find something that suits your needs there. A Bryston processor would be worth a look since you have the Bryston amp. Going to be less features, but likely better sound. For sure good matching with your amp.
B&K is fairly unique in that they provide a product that bridges mid-fi to hi-fi gap. They will eventually get some of the features you are looking for but you will need to wait. I think in the future all of your content will reside in a cloud, so you can stream it where you want it. Keep that in mind.
We were a Gallo dealer from the beginning, and I run Gallo Ref MKII myself. Just FYI.