Some things are a given, room size and speaker treatment, and both are usually encumbered by a number of unchangeable factors, to state the obvious. Let’s just say do the best you can following some basic principles you can study up on elsewhere.
That said, pretty much like others have said where order is +/- individual experience.
1) speakers
2) amplification in terms of enough power for #1 to suit your needs
3) quality of source regardless of type, disc player, streamer, TT, etc.
4) cables/ICs. Refuse to get sucked into this dialogue but suffice it to say it ain’t lamp cord or cheap ICs. I’ve had a blast in the new old stock department with MIT and won’t ever bother changing those.
5) Lastly, rigging a separate electric source and inexpensive Furman condition took the noise floor to zero (my ears weighted 😎)
The cost of all this depends on your ammo magazine. If I was earning Bryce Harper/Juan Soto coinage, It would be a blast but again for my ear, not really necessary for hifi enjoyment.