Do you belong more to souce first or to speakers first school of thought ?

But speakers are the soul of a system and in this sense they are always the most important element.

If the source is terrible then nothing matters and the same is true for the speakers. That said I think the variance in speaker quality is more impactful than the source. I focus on speakers first. I have Sopra 3 speakers and they contribute the highest single cost of my 125k system. So as you can see there are many other contributions to the total. I have vinyl, CDs and streaming so this is a multiplier. Also cables make up about 22k of the system. It all matters. Then there is the influence of the room. If it is a bad room a lot of the effort will never pay off. 

If you measure distortion in a contemporary music reproduction system on a per component basis, speakers contribute orders of magnitude greater distortion than any other component. At least in solid state and ultralinear tube systems. We are talking single digit distortion percentage figures versus 0.000025%. So it’s not even a question for me.

1. choose the speakers

2. place the speakers (you can do this with math and geometry, there is a right spot)

3. fix the room

4. fix the speakers

5. choose a signal standard (I favor +4 dBU but if you like -10 dBV you do you)

6. choose your components

7. fix your gain staging (if you have components that will let you do that)

8. now you are ready to hear various source components on a level playing field

The listeners chasing euphonic distortion with low power amps and very sensitive speakers 105 dB/W or more!) are playing in an entirely different sport and may have different rules entirely.

Budget, then wife, then room, then speakers.

It all matters.  Having said that I don’t think that the emphasis on the source should be what it was 50 years ago because the quality of the sources has improved so much.  Midfi turntables and digital sources sound pretty good these days, as a rule.  I’d rather play a $1000 streamer or turntable through $10K speakers than the reverse