The main problem in such an audio chain is to realize what has a real influence on sound and what is just public knowledge, introduced by marketing.
Maybe I can give you and idea what really matters? First, any difference you instandly hear in a comparison is usualy a matter of different levels. Only when you adjust an A/B test in level, you will get serious results.
Cables: You can't win anything in sound with cables, you can only loose. Even if you spend 250000€ (a quarter million) for cables, you will not improve a chains sound, compared to good quality wires for maybe 80€ or even less. This will be disputed by any audio salesman, because he makes some hundred or even thousand % profit on wires.
CD player. If we remove defective and realy bad 30€ gear, any CD or DVD/BlueRay player from Denon, Marantz, Sony and the like will have a good enough analog audio output not to spoil the reproduction. The differences may be audible, but not in a better/ worse, but more taste region. How the unit feels and looks plus the price tag will change more in your perception than the objective output. If you use the digital out things get even more boring: All the same or defective.
Same thing for DAC's. It is hard to find one that really sounds bad.
Amps: Today we have reached a high grade of good, neutral sounding amps doing 99.999% nothing wrong. . If we remove the worst examples, differences get very small. There may be an amp getting allong with problematic speakers better than another, but the average modern quality amp will not be a limiting part of your system.
If you ask me for a stereo amp, I may give you a price list, but no "sound" list. You will have a hard time to beat a well choosen 120€ D-amp, whatever budget you have. If you need more then 2x250 W/4 Ohm, you may be able to spend some more money. The problem is your idea of a capable amp: You will think such a 100-200€ D-thing is too small and maybe dislike the power supply it may have attached. Do not expect an A, A/B or D amp to sound any different! One of the great lies in audio.
I already mentioned an AVR. Get the Denon and you are save. Best you can do. Soundwise if you want a neutral, good amp, for different sources of any kind and for complicated rooms.
These AVR's are solid amps if used for stereo only, because the juice from the power supply serves only two channels. The best option for you IMO. The Denon X-3800 for 800-900€ is hard to beat. There are no new standards on the horizoon, so you may use it for the next decade.
If you have never heard what a good room correction can do to a good speaker, you will not belive the difference.
Also, you get an advantage to bi-amp your speaker, any good AVR got this option. So you use 4 amps for your speaker. It may give no difference in the worst case, but could help the high and low part quite audible.
The only thing left with huge sound differences is the speaker. I would be really surprised if your FOCAL speaker does anything wrong. May just sound very different to what you are used to.
The model you got should be well known in France, maybe look up some independent sources and try to read the fine print.
PS sorry, FOCAL doesn't like bi-amping. I thought this option to be a standard for 3000€. Not with your speaker.
By the way, what bothers me, why did you like the speaker in the dealers room. Usually there are not so huge sound differences.