Forum admiration and requested guidance

I am impressed to see how the walls are knocked down with a kick if is necessary a renovation because I see that they are hollow inside and built with light panels and supporting wood; they are not made of brick or reinforced concrete

Brick wall is the worst for sound.

I wonder if what I see on TV is all true and how bad an audio system can sound in rooms built that way with walls so light that they could resonate like a sound box; I am worried and horrified.

No walls are better, but lightweight walls can pass a low frequency through and it’s better than brick walls that can only reflect low frequency wave.

I’m talking about low frequency range because the bass is terrible problem for a small room with a typical 8 ft ceiling in the US and Canada.

You mentioned the Decware ZP3 for the phono preamp. On their website it mentions a step up transformer for moving coil cartridges. I’m assuming the ZMC1 would have to be included if I chose to stick with the Hana (Low MC), correct?

Right. I didn't run the numbers just sort of ball-parked the stuff I recommended would be well within your budget. That way you have room to upgrade to another cartridge like something high output from Soundsmith that won't need the SUT, or go with what you have and get the SUT. 

I don't normally btw recommend SUT. But that is because there are so many, they are all over the map cost and performance wise, the market is thin and so you can wind up taking a big hit on resale. In this case though Decware eliminates all that with their lifetime exchange. 

I have over the years come to favor companies that manufacture and sell direct. Not as some kind of magic pill, everything sold direct is not automatically wonderful. But they do eliminate a big chunk of dealer profit, a lot of which you wind up getting in product that would cost a lot more if sold retail. Search around, people with ZP3 are real happy.

Whatever you do, for synergy with vinyl and engagement factor try and stick with tubes. 

There are opportunities abound to receive similar impressions and impact that you experienced when exchanging Cables.
Equipment Changes will most likely offer noticeable improvements but your unique audible preferences must be catered for as well as any aesthetic requirements.
20K to be budgeted over a two year period is going to create a System that can reignite ones passion and encourage much desire to revisit the Album Collection.

Here is my take on the route to satisfaction.
If you are not wanting to purchase more Vinyl Media, the alternative to bring your already owned Vinyl Media into the preparations will be quite a valuable consideration.
A Vinyl LP being a Source Material can impact on how the upcoming system is going to impress. Taking a time out and following a Cleaning Method and Storage for the owned Vinyl will have quite an impact on the present replays, and more so on the replays in the upcoming system.

You are an individual and within this you have developed your own unique preferences for how a replay will impress you.
One individuals model that is to them an 'attractor' and recommendation can quite easily prove to be another individuals 'detractor'. 
To find ones own preferences can be done in two ways, the first being the quick route, trust to luck and throw money at purchases, hoping the end product hit a home run, or the other way is to arrange to meet and audition and receive demonstrations of equipment on a shortlist.
Arranging and Meeting can add time to the period allowed for the acquisitions, but the experience gathered, relationships formed, and the assurance that monies were wisely spent, is a big part of the continued long term satisfaction of the system when at home.
Dealers Premises, HiFi Shows and Enthusiast Shows are a great place to start, and the foot work might create a meting where like minded individuals are met from within the home community and friendships are starting.   
That has been my route and the one that has been the most enjoyed.     

How are we supposed to encourage young people to join us
in this hobby if they can buy an decent system after their
kids got Ph.D? 

@chakster , that is an interesting take on walls. I never thought about it that way. But if studded walls are not dampened wouldn't they keep going and pass the bass back into the room? Certainly, no walls is the best solution. The resonance of the wall will create a peak in the bass which can be handled partially by room control.  

It is academic as none of us have a choice other than to use 2 X 6 studs.
As far as I know nobody uses real masonry walls in the interior of residential homes and only on the exterior of large commercial buildings. The interior of these is aluminum studs which are way worse than wooden studs.

I was playing Soundgarden's Badmotorfinger yesterday at 95 dB. This record has some serious bass. They were using feedback in the low 20 Hz range. I went outside to grab some parsley out of the garden and happened to look up at the picture window adjacent to the left channel speaker. The sun was reflecting off it as it was doing this amazing dance. 
I wish I did not put a window there and I am seriously considering removing it.