Dear Inna, this is the most brave thread ever !
So, lets make a start :
If I'm starting from scratch a stereo system, these two would be the most critical to identify it's character and the rest of ingredients (while not of secondary importance) were having the mission to serve these two (not mask their character). Of course we all agree on this.
But what if we proceed by choosing them first?
In this case lets see the process :
1). I would put on my list very carefully those speakers that connects me fluently with music. ie : (Shindo Latour, Red Rose R3) and simultaneously picking the cartridges that also fulfill this exact promise and keeps the spirit intact. ie : (Decca Reference, Colibri)
2). I would choose among my priorities the apparent matching : (The direct liveness of Decca and Shindo, Vs the etheral 3D soundstage of Colibri and R3)
Unfortunatelly or for my good luck, I'm not programmed to make this kind of rationally objective observations a buying decision, once that in reality these theoritical -on paper- mix of equal personas, could give a mega smack in my wallet and bring forth many questions regarding my brain salad. Because the straight wire with gain is a huge lie and everything matters everywhere inside & out of our components especially when they called to mixed together.
Trial & error the only way.
There is not a recipe formula for me. After auditioning all those components in my list, I could not predict the matching pairs among them. Sometimes created an overdose of a particular strength or even a new monstrous character that makes me suspicious for the genuine value of this characteristic strength.
Now in present reality that we allready have choose the synergy between a number of components that as a system satisfy our request, we can proceed to try a new cartridge to pursue our need for pushing the limits higher. Equally we may hear a speaker that could be a new breakthrough discovery to our request and realise that there is no way to reach it's quality of offerings without bring it to our system's chain. If we are not satisfied with our present speaker, there is no catridge that can rescue it from it's misery -"other than to mask sonic faults and so to fit into a personal sonic matrix"- I concur with Daniel.
When I first hear the Shindo 604, I've realised the huge improvement over my PHY Ocellia 03 Silver, but I was also worried about a somewhat heavy, overweight, dull & dark feeling on it's projection at every LP.I recognise that my analogue source certainly could give it a very different personality than Shindo's 301 TT/arm/cart that I was tested it with in the distributor's room. When I've carried my own TT/arm/cart to the auditioning room, the quality went to the stratosphere. But this is my favorite source no matter what the rest items are in the chain and also, I strongly dislike the nostalgic sound of the Shindo's combo. So, we can't say about a good matched source/speaker here. It's just my two favs playing together.