Thanks everyone for the input. I may take another look at the Monitor Audios. The visual acceptance of the speakers by the wife is another factor I have to consider until I'm able to build a dedicated listening room. That being said, I'm not in the position to drop more than $4k on speakers at the moment.
My planned upgrade path is as follows:
1. Upgrade my speakers first. Almost anything I upgrade to will sound far better and will make my current set-up sound much better I believe.
2. My Marantz currently has a pre-out for a separate amp. The Adcom is fine for its age and while I plan to recap it this Fall, I'm leaning towards getting a better-quality amp anyway but nothing exotic. I still have kids to raise!
3. I'll keep the Marantz/amp set-up for a while and then decide if I ditch both for a higher-end integrated or a better pre-amp/amp setup. But I would like to land on a pair of speakers that I can keep for some time.
I'll keep you posted on my decision. I'm hoping to upgrade later this year unless I stumble upon a deal I can't refuse before then.