Thanks for providing the important part, i.e. how loud do you listen. Without the info, we can expect a ton of nonsense of how everyone must use a 4 ohm rated stout power amp for 4 ohm speakers. Such are nonsense because it defines logic, that voltage, current, power requirements varies with not just impedance, but the actual impedance and phase angle versus frequency curve, sensitivity, sound pressure level requirements and distances between speakers and listening positions/room sizes etc.
That's why on this site, many responsible members often suggest the OPs use an online calculator to figure their need, in addition to seeking out the speaker impedance/phase angle curves.
The focal Aria 926, based on the larger 936, can reasonable be expected to need a power amp instead of AVR's own amps, but again it depends on other factors mentioned above. May be try a calculator, and whatever "power need" it shows, get a power amp that is rated for say 2 times (the higher the better, I would use 4X, and 10X for short term duration, but that's just me) that, into 4 ohms.
Crown Audio - Professional Power Amplifiers | English
If you use the calculator above, you will see that for distance of 3 meters, even if you listen to reasonable loud level (your neighbor will likely complain unless the concrete wall is at least 8 inches think with sound deadening material) of about 10 dB below reference, that is 95 dB peak, 75 dB average, your Denon AVR can do the job fine.
Regardless, I would still suggest an external power amp for the 926, a tiny class D amp rated about 350 to 500 W 4 ohms will be more than adequate. Focal's spec for amp is:
Recommended amplifier power: 40 – 250W