What, if any, component to upgrade? Advice?

Your system is very different than the direction I have gone in this hobby, but I'll throw in my 2 cents anyway : )
How about a Schiit Bifrost DAC? It's a great DAC and cheap. Should improve on your Rotel CDP quite a bit. Plus it gives you the option to explore streaming in the future. I have the Schiit DAC in my headphone rig and like it very much.

Simao,

Whether you wish to stop the upgrade 'mania' is up to you. ;) However, if you are looking for more presence...i will assume this means bigger sound, bigger soundstage.

Two choices imho...Get a much more powerful tube amp (assuming you like your current tube sound)...which should drive your speakers much further.

Or get bigger speakers...the challenge will be can the 10watt/channel amps you have drive the bigger speakers?

If you are doing this one step at a time, perhaps focus on amp...i love the Forte 4 amp (50watts/channel pure Class A)...second hand only today. Or one of the older CJ amps...MV60SE maybe? might be a bit tight at 1K...but perhaps the original MV60?

With good speakers, putting a much higher current thru them can have sometimes quite shocking levels of increased soundstage/power.
Good luck.

When it comes to upgrade, it's hard to stop at just one item to replace. The first two suggestions are a good place to start. The Bifrost will set you back about $400 or so (if you forgo the USB) which would leave you with $600 to put towards a powered sub, perhaps?

All the best,
Nonoise