Critical oppositions made using inadequate equipment.

What is the best shape of leaf for effective diffusion when situated behind loudspeakers?

Darko Audio explained in this video :) 

Is it really possible to critically estimate tt or cartridge characteristics using for example cheap monitor speakers or other weak component in the system ?

If what you call "cheap monitor speakers" are professional studio monitors (near field monitors, if they are small) then you will be able to hear everything, normally monitors designed for monitoring in the mixing/mastering studios. They lack bass, but the rest of the spectrum is there. Good near field monitors must be neutral. Some small vintage studio monitors are inexpensive.

You will hear the difference even with small bookshelf speakers, but hi-fi speakers are colored, far from being neutral.

Cartridge is the key factor in high fidelity reproduction of phonograph records. This is logical, since the cartridge, via the stylus, makes the first and only contact with the record. It is the unit which transforms groove undulations into electrical signals. The stylus has to move (to the left and right, up and down) at very high speeds, deal with extremely high forces, yet maintain surface contact at tracking forces consistent with low record wear, and ensure high channel separation for stereo reproduction.It is cartridge performance, therefore, that determines basic sound quality before the signals are amplified and played through your loudspeakers. Advanced stylus profile (natural diamond) distributes the stylus pressure over a much wider contact area within the groove than is possible with conventionally shaped diamonds. This provides greatly reduced wear on both record and stylus at the recommended tracking force. In addition, the advanced stylus profile (such as FineLine, Shibata, LineContact, Stereohedron, MicroLine or MicroRidge…) also provides better tracking ability and lower distortion at high frequencies in the critical inner turns of the groove. Compared with other stylus materials the advanced profiles do cost more, but the extra expense is fully justified by the resulting superior performance and extended life

There are many cheap mass market products on the market, for example an entry level turntables or speakers, but when it comes to analog playback you can hear the difference upgrading just a cartridge (read above).

Of course if you will start from interconnect cables using such entry level system the difference will be hardly noticeable (if any). 

@surfmuz if you asked regarding your own system, don’t hesitate to tell us what you have and what you are willing to upgrade

You have to listen in your system and only your opinion is valid when you choose a component. I bought far more turntables than I actually need, too many tonearms, and many more cartridges of all types (some very rare units). Different phono stages, SUTs, headamps ... Some people have more, some are totally insane in this hobby.

I also adjust and test every new cartridge not in the main system, I use headphones and two identical turntables to test carts, styli etc, I can immediately switch between two identical turntables. I can hear the difference using professional Sennheiser HD-25 headphones. For the first teste it’s enough.

I got 3 pairs of speakers and they are vary from bookshelf professional Tannoy monitors to the huge main Tannoy monitors and floorstanding high-end speakers. I have couple of friends with nice systems and we can meet for a listening session. Everywhere we can hear the difference, but I enjoy the most my MAIN system, this is where I use only the best and every change in that system is audible (cable, phono stage, tonearm, cartridge... whatever).

I’m not sure what was the purpose of this thread? Just to say that a friend who adviced some cartridges to OP has completely different opinion about those cartridges than the OP? I read the same on audiogon everyday, people are disagree on many things. But I have no idea who they are and when I see the images of their systems I often shocked (in a bad way), the OP could ask his friend in person (or to check these carts at his system), but he asked an opinion of some strangers on audiogon to read two opposite points of view (again, as always).

Haha, I use holy water @surfmuz and it change the whole sound (in a good way).