Which area of components to spend the most $ on? Boy I was wrong all my life!

A good discussion!  Audio systems are just that - systems where every component affects the end result.  The most important part to spend money on is the weakest link.  Finding this can be hard, I once changed my speakers and source but only fixed the issue I had when I upgraded my amp (which I thought was my best component due to brand name).  If I had started with the amp I would have avoided some unnecessary churn.

The rule of thumb about spending the most money on speakers goes back to a time when good speakers were hard to find  and expensive.  Relative prices have shifted which allows more to be spent on other parts of the system.  

Don’t forget cables and power cables are all part of the chain.  I also got a big improvement from adding isolation feet to my equipment.  As an early poster said, the more the system improves, the more noticeable the benefits of additional upgrades.  That’s why very high end systems have very expensive cables- because these things start having a big impact as more nuances are revealed.  That’s where the black hole comes from!

Sometimes I think that if given the financial resources I would by an all-in-one system. Then all pieces should be suitable together. Active speakers have amps that should be selected to work with the drivers, any dac inside should be good enough to do the system justice.

Of course you give up changing components but it might be nice to just buy it all at once.

Like this one:
https://goldmund.com/collections/prana-active-wireless-speaker/

Have you not had good speakers to begin with your new CD player might not have blown you away now.
With mediocre speakers it almost doesn’t matter what you feed it.

People suggests going heavy on speakers as a percentage of the INITIAL budget. Over time of course it makes sense to bring the rest of system up to par.

Further, I’d also recommend speakers that are easy to drive to keep amplifier issues to a minimum so that You can spend time improving the front end, especially the preamp.

For low budget audiophiles like this none-too-well-heeled orchestral musician, I only spend my big bucks on MC cartridges and a good preamp (right now, Benz Micro Wood SL and Lukaschek PP1 MC preamp). A well-maintained Thorens with these components sounds very good. Only the slightest hint of IGD, on well loved records.
A fancy valve amp with some of those newly-introduced models of tubes would be nice, but I have a mortgage to pay in an expensive town, so vintage tube and SS amps it is, for me.
FRONT END ALL THE WAY, BABY!

Speakers  are critical since they create by far the most distortion 
up to 5% or more depending. On volume, in your case you bought
 a noticably better piece of electronics , it isnot the speaker
spending more was. A bad idea . In your. Case it’s you are limited 
in $$ monies to spend ,  you. Could still make great strides in sonic improvement if you had say another $3k to buy something 
more. Expensive ,better parts quality.  Myself have Everything modified ,and being frugal  on wire quality is For sure holding  back your system . Kimber8 tc is Avery good start,average cable 
middle grade cable you can go much better .i myself make a far better cable then cables 5x better minimum  then. My cost.
cables have a Huge markup .  For example I went toVH Audio 
small gage solid Teflon  Litz -6-9s ,pure Copper wire around $25a foot, cotton insulator core, you have to unstrand  cut and terminate it . I did speaker cables, interconnects,speakers 
and electronics , a Night and Day improvement , also inside your Revel speakers the Xover parts are not even average ,I owned several of their speakers Rebuild the Xover with Qualty parts maybe $1k your speakers will be drastically improved for a $2-3k
investment you get at least 4-5x more in quality that you would
have spent if buying commercially . I owned a Audio store 
less then $25 % actually goes into the product ,meaning unless you are spending well over $5-10 k on each piece of gear inside 
decent but average quality parts. That is why Dan Modwright was 
so successful rebuilding and putting highquality parts in key area.
everything is built toa price point , I sold several $$ brands well. Known and shocked at the level of capacitors resistors,wiring and power supplies used. Most people have no idea for they don’t 
look inside. Keep this in mind ,if you or a friend is handy and can solder you can build thingssuch as cables in a day . Theselitz speaker cables ispent maybe $500 with connectors best hands down several of my friends Big name $2k + cables ,without all the fancy jackets I saved over $1500 alone just in speaker cables 
and having this wire quality throughout the whole system creates
a system Synergy that brings it to another level in musical integrity.
sometimes it’s the little things that do count , even replacing the cheap steel fuses which are a ahuge bottle neck justlook up the 
metal resistance index copper,and silver 5x more conductive ,far less resistance meaning much lower distortion at each fuse junction,after a 75-100 hr runin. These are all facts just read themsny reviews and we did many blind tested comparisons .
i am just telling the facts ,it’s your money, why give it away 
if you can dotings on your own . I even build my Zobel networks 
for all the high  frequency noiseover 10khz for littlemoney a noticable speaker enhancement, Everythung counts ,
and clean your connectors st least 1x a year on everything I use 99% Isopropyl alcohol ,Craig good foam swabs and what I feel the best enhancement ,long term protectant  Stabilant -22 which protects over 12 yerars if not disturbed has won a ton of awards 
even great on a Vacuum tubepins it is a super conductor  that
is not conductive until a charge is applied ,not like a messyconductive Silver Paste thst has a short life.