Trying to Help My Nephew With His First Venture Into High End Audio

Would appreciate some advice on how to proceed.

I am "gifting" my Nephew several components and a set of speakers, from my 2nd system. Most of this stuff is from 1995, but works well and still sounds very good. He listens to mostly Rock music on Vinyl.

Here is the base system we are starting with (digital only, no Vinyl):
Totem Model 1 Speakers (4Ohm and 98db)Meitner MTR-101 (MUSE-TEX) Mono Amps (100W into 8 Ohms, 200W into 4 Ohms)
Rotel Solid State Preamp, RC-970BX (No phono stage)
Marantz CD Player (CD-63SE)Opening price point interconnects and a set speaker cables
I would like to keep him focused on "separate components" versus an integrated option. I believe this will help him to learn about how each part of the system contributes to the sound, and if he chooses to change something, he can "perhaps" upgrade 1 component without changing the entire system.

Also, he is a bit hesitant about tubes. However, I would like to introduce tubes somewhere into the system (preamp or outboard phono perhaps) so he can learn about the benefits and shortcomings of tubes in Vinyl playback.
As you can see from the system I am gifting him, he will still need to buy:
A turntable/arm/cartridge.Either a tube preamp with phono section (if replacing the Rotel) or an outboard tube phono stage (if keeping the Rotel).
Also a SUT depending on what direction you suggest.

He has $5,000 to spend.