Home Theater separates won't fit in new house

Unless I modify the custom built walnut cabinets in our new home I need to find smaller AV components. I have an old Theta Casa Nova, NAD M3 and Paradigm Studio 100 v5 speakers. Could I find similar or improved sound quality using smaller components to fit inside 15" deep lower cabinets and an assortment of speakers which could fit the 15" shelves around the large TV panel space? I would throw around $10k at components and speakers and keep the old system for the bedroom.

I would have no trouble stacking smaller mono amps since there is a large amount of vertical space in the lower cabinets. I would also consider adding center speaker and subwoofer to work with a smaller pair of shelf placed front speakers. 

Why not try to relocate the AV components (all but the speakers) to a different part of the house and operate them remotely? Is there a hallway closet that might work? We did this, and it is an excellent solution. Much happier without all the AV boxes in the media room.
the new generation of class d amps are quite compact (nuforce nuprime etc.)--i'd look seriously at those
You're willing to drop $10k on a totally new system… what about dropping $3k to modify the custom cabs, or is that infeasible (needs more depth, etc)? 

You can probably change the height of the shelves, or take some shelves out entirely, but still retain the overall look and feel. 
Should have thought about that before you bought the house! Now you have to drop some more coin to remodel or re-purchase new equipment.