Hi @Steinar.Bakken thank you for contacting us. As far as I remember you can only enjoy FLAC sound quality with a Chromecast connection or cable, not via Bluetooth. I am sure you can hear the difference on your Hifi supported devices but I’m gonna double-check with the team next week 

@Steinar.Bakken Which Harman Kardon device is it? The related Deezer hardware overview only talks about certain speakers, so make sure that you have one which really supports Deezer HiFi streaming:

https://www.deezer.com/en/devices/soundsystems

Note that this page mixes speakers with other soundsystems and/or receivers, so just looking for the company name plus the yellow HiFi sticker can be misleading. But the good news is that there seem to be some HK devices with Deezer HiFi support.

Furthermore the Bluetooth standard includes many audio codecs in the meantime, but not FLAC. The closest would be aptX HD which is described as “near lossless” and “CD-like” in various publications. See e.g. this article:

https://www.whathifi.com/advice/aptx-hd-bluetooth-what-it-how-can-you-get-it

Whatever its detailed specifications are (max. sample rate, bit depth and bitrate are not enough), in the end transcoding between aptX HD (or lower standard Bluetooth codecs) and FLAC would be necessary to support what you are looking for, and my guess is this is not implemented. So hoping for an improved Chromecast connection with Deezer HiFi streaming in FLAC format to your Harman Kardon device is probably more realistic if it supports Chromecast at all.

You can enjoy on Bluetooth almost Hifi sound using LDAC profile.

Since Sony made it up to 990 kbps, you won’t find it on any other Bluetooth devices. The LDAC will be 990 kbps in optimal condition only, otherwise due to signal issues it may be lowered to 660 kbps or 330 kbps which is the lowest when signal is poor. Sony has been selling headphones since then.

Look for Sony brand only to find LDAC devices.

The WH-1000XM3 wirelessly only connected to Android phone can provide with 990 kbps FLAC enjoyment which gets only better when you use wire prepackaged in the item you buy.

I just changed to Hifi and since then on my laptop I do not use SBC line Bluetooth which is 320-256 kbps at best. I get tremendous sound improvement using same headphones with a wire you’ll get.

These headphones are now on summer sale at €199, and they were before 249-299 euros.

You’ll get decent BT experience outside and wired home theatre to your home. I really recommend them, so you have no need to spend on more expensive speakers or headphones enjoying all the benefits Deezer HiFi has to provide including greatest bass response and smallest nuances.

I can’t see myself going back to Deezer Premium, I’m sorry :)

At the moment LDAC is best Bluetooth connection 990 kbps, but it’s still not lossless.

I’ve got new Windows laptop and here the codec is APTX which is not much better.

I hardly listen on WH1000X-M3 anymore wireless. Bluetooth on laptop, which is my mine music source for this, I simply do not do it wireless anymore. The sound OGG 320K gets converted wirelessly. You can have a loss of details. As well the sound is more stunning wired. It’s like listening Hi Fi. It is louder at same volume, so I need less volume to run them, just keep them ON so they will use Sony’s sound optimization. Without it ON, the sound is lazy and powerless. The only drawback with it, is that touch buttons do not work at all when wired, but sound improvements are totally worth it.

On the go I still use wirelessly using earbuds from Sony, but here it gets converted to AAC. When you are already on noisy bus or something, there’s not really anything to loss, when wireless is a benefit.

People talk about Hi Fi music 1411 kbps, but for me 320K OGG is just as great.

Especially wired, so you get all the sound without a single loss because it gets re encoded.

I don’t really need the wireless option no more, but other way they are still great.

I don’t hear ventilation sounds or any other sound when enjoying the music at the fullest.

Noise cancellation simply works great for over 24 hours easily wired.

The best thing is that battery is working 24 hours only wireless, but wired NC on it is 36 hours.

So you get some extra time before next chargering.

What happens when I listen to hifi flac sound quality with Bluetooth headphones that support up to 660kbps or 990kbps bitrate? Will I be able to take advantage of the Bluetooth 660kbps or 990kbps or will the audio quality automatically resort back to Deezer's high quality of only 320kbps when listening with any Bluetooth headphones?

You should check the capabilities of your phone if it can also use the LDAC codec for Bluetooth with the highest bitrate, it is not enough if only your headphones can use it.