I'm happy but I want more, more, more

Bill, I too have an all analogue system. Upgrading my monoblocks just cost a bunch, but that good result was no more impressive than a $10 tweak.

That tweak was resonance control on the tonearm. I used some sticky gel, the stuff used to tune drum kits. Moongel it's called. Lots of fun, lots of results, and lots of money left over!

Moonglum, I disagree that this is or is becoming a rich man's hobby. The thoughtful and introspective man who is a clever shopper and a little bit handy in a workshop (not necessarily a craftsman) can achieve as much or more satisfaction as anyone with purely money to blow away.  True, you have to have SOME money to spend.  But six figures, nah.

Sadly we are not all millionaires and the best analogue is rapidly becoming a rich man's hobby

I see people putting together very successful systems using modest equipment like the Technics SL1200 with a Grado Gold cartridge, amps like a Dynaco SCA-35 and a perhaps set of Lowthers. But I guess a lot depends on your definition of rich...

Dear @bill10907 : Maybe you are not sure to give an answer to my questions that were not " rocket science " knowledge level needs to do it.

Anyway here I go:

to build any audio system we must to start with the best audio components/items we can afford at both system chain link extremes: front end and speaker/room.

In between those system chain link extremes yours looks pretty decent/good.

Where can I start to up date your system?. Very simple: where the sound comes at your listening position ears: speakers.

NO. I’m not talking to change those Thiels, as a fact I loved Thiel speakers and had great opportunities to liste it for long periods of time even at my place with diferent models: 7, 5, 3.5, 1.2 and the 3.6 you own.

Well the 3.6 ( as any other speaker ) is far away to be " perfect " but the 3.6 has a severe problem and is a true limitation for that " more, more " you are asking for.
Problem is that so high crossover frequency between the woofer and midrange drivers: 500 hz that grows up in frequency due the JT preference for first order ( 6 db. ) crossover filters that permit that those woofers handle frequencies as high ( we can hear because those first order filters. ) as 700hz-800hz and this means really high THD levels on what you are listening.

Here you can read what I’m talking about ( read it carefully. ):

https://forum.audiogon.com/discussions/do-you-think-you-need-a-subwoofer/post?postid=310058#310058

when you liberate the 3.6 woofers of those long excursions from 100hz and down the improvement ( sure, true and real. ) in quality level of the sound you will be listening has no paragon: just fabolous, just a new improved audio system that you can’t even imagine you " have it ". Your system could be ( then. ) outperforms systems in the 300K dollars!. Believe it or not.

@m-db sugested that and ( independent of his reasons to posted it. ) he is spot on.

There are other areas where you system can be upgraded but those are latter and when you already integrated a pair of active/self powered in true stereo fashion in your today system.

Many alternatives for subwoofers but the true home system experts comes from Velodyne and for very good reasons: DD-15 or HGS-15 models can do it over any other " glamorous " subs in the market.

Btw, why do you think that the today bets quality level performance spekaers comes with dedicated active subwoofers?. Here you can see a " dream audiophile system " where those speakers comes with active subs:

https://systems.audiogon.com/systems/615    

but not only those speakers but for example the top Vandersteen and many more.


Regards and enjoy the music.
R.

Agree with Raul, give us more info in what specifically you're looking to improve upon.  "More" is not enough to go on to get targeted and more helpful recommendations.