Which makes the bigger difference?

For soundstaging, I think the most important components are the speakers and the room, and the positioning of speakers within the room. Next is probably the amplification (preamp + amp), and the associated SS vs tubes differences. The CDP will also play a role, but I cannot say to what extent compared to preamp + amp.

What is it that you don't like about your current situation?

I would advise trying to optimize the position of the speakers first, then consider some cost-effective room treatments, before blinding going about changing components.

Just my 2 cents.

Michael

Agree with Michael.

I would look into Audio Research tube pre and SS Amp combo. See if anyone else with Apogee speakers are using AR gear.

My experience is that anything that obscures low level detail will reduce soundstaging. After all, it is the low level detail that creates the soundstaging effect. All components in a system will obscure detail to some extent, so more revealing gear all around will improve soundstaging.

Another crucial aspect is vibration control. If you are using the stock rubber feet that come on most gear, this will obscure low level detail. Switching to cones and other such footers will make a big difference.