Relative Importance of Analog Components

cartridge first, the best you can afford and that your turntable will support with proper adjustments and net system resonance.  

phono stage also needs to support the cartridge with proper gain and loading options.  

Dear @dogberry  : " which of the four components has the most effect on final sound... "

It's obvious that a change in the transducer ( cartridge/speaker ) has " the most effect " but what I posted is more about quality level more than just sounds different.

You can have 2 same model cartridges that will sounds alike when in reality no two same model cartridges sounds exactly the same, always exist very tiny differences and be differences thaT YOU ONLY CAN BE AWARE AND DISCERN ON IT IF YOU OWN THE " RIGTH " HIGH RESOLUTION PHONO STAGE AND THE MATCHED TONEARM and even if you own those two audio items maybe you can't discern about because sometimes we need to know what to look for, this is that we must have a test whole proved proccesss.

The cartridge signal quality level depends ( everything the same ) directly/mainly by the Phono Stage and tonearm quality design levels. No matters what.

Discern between different and better depends of each one of us MUSIC/sound experience.

R.

1 Turntable - nothing further down the chain can fix any speed and resonance issues here. In fact they'll only make them more obvious.

2 Arm - once again structural/resonance issues will make the job of the cartridge much much more difficult.

3 Phono Stage - very few amps have good phono stages built in. Some don't have any.

4 Cartridge - even a budget AT cart can give you very good results in a decent deck.

Besides they will wear out fairly quickly, are far too easily damaged, and are often a pain in the butt to change over and align properly.

It goes without saying that turntable siting is also very crucial if you want to make life easier for your turntable.

A lower performance turntable optimally sited will more than match a better one that is not in the same way a budget Ford will run better on a new road than a Tesla on a bumpy one.

The quantum world that turntables operate in is not readily visible to the naked eye or one that can be felt by human touch.

I am in the cartridge - phono stage camp, for now. But it vastly depends on the entire chain, with low-end bookshelf speakers, I wouldn't invest in a phono stage. 

And clean those LPs, that makes a huge difference!

Putting the Quality of the Vinyl LP as a Recorded onto Material to one side, and focusing on the tools required for the extraction of the recorded media, through tracking the Groove.

The Analogue Source is quite easy to be seen as a complex chain of interfaces, it is a unification of a Mechanical, Geometric and Electronic interaction, where each individual element is requiring to achieve a certain level of precision to achieve a replay that would seem to be with a tolerable audible end product as the result.

Attempting to solely work with any one of the Three Critical Interfaces, will bring a change, and in certain cases a betterment can be detected almost immediately, if a particular discipline is accurately imparted.

There is a lot of trust to be placed in the parts attained to produce the entirety of the Set Up that will allow for a replay to take place, and the replay being produced in the eyes of some may only be referred to as being capable.

To achieve more than Capable is a intent that many carry, and the precision needed to be used, to attain what one would describe as their ideal, is commonly seen as a pursuit of a particular element and not the careful optimisation of the unification of all parts dependent on each other.

Hence, threads looking to learn about which single item is most beneficial arise.           

Within all the above, there are compromises that some are willing to accept, as the readily available convenience to experience a wider variety parts that are a Critical Interface can be a attraction.     

What ever goes on from the Stylus to the Speaker Cross Over is not audible, it is a a methodology to transfer a Electrical Signal that will then be processed at a Speakers Cross Over to create a Audible Sound.

With that in mind, it is quite important to have faith that the Speaker is delivering a Sound that does not interfere detrimentally with the Signal being processed at the Front End.