Hey @Leon-x 

HiFi is now supposed to be the new standard and costs more accordingly. Unfortunately, if you can't hear the difference and aren't willing to pay the 3 EUR more, you'll have to find another streaming provider.
There will be no cheap 'Not HiFi' subscription with deezer in the foreseeable future.

I can hear the difference of HIFI with my Sony LDAC headphone on Android. But the thing is, I can’t hear it with my HIFI headphones connected to a DAC on my computer. And this is because Deezer unlike Tidal doesn’t give us the option to direct the stream directly to a DAC.

The difference between 320 kb/s and CD-quality (Deezers HIFI) is very little anyway. Lots of people even can’t hear the difference. Either because they don’t have the right equipment or they simply cannot hear it.
Deezer’s move to HIFI is mostly a marketing thing. Not so much an improvement of quality.
Music quality is not only about size file: I have heard music at lower bitrates that sounded better than Deezer’s higher bitrates.

I am not yet willing to give up my subscription because I like Deezer’s Flow, but if they add a couple of euros more or if I will get bored with the flow, I am definitely gone.

You can’t raise a subscription that much just based on “quality improvement” that is not or hardly perceptible for masses of people. It’s ridiculous.