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

My suggestion, do not buy anything without trying it in your system first. So only consider upgrades that you can demo or that have loaner programs. You don't want to get "stuck" with an upgrade that really isn't an upgrade.
I also agree with Lloydelee21, a bit more power might help.