I believe you mean the Echo dot right? The Echo is the big one. I have both. [The built in Echo speakers sound great, I usually keep it at level 5 because more than that and its too loud for the neighbors and has good bass]

The built in dot speakers don't sound good at all but can easily be connected to any bluetooth speaker or with a 3.5mm cable.

I have a $10 speaker from amazon that also has lights which you can manually change or coordinate to the bass of the music, and it works great.

Deezer, I have never heard of but I searched the Alexa Skills and it is not on there. It does support Prime music, spotify, pandora, Iheart, TuneIn, and sirius

As for functionality, I yell at Alexa all the time. She is a dumb bitch. Constantly gets things wrongs or doesn't follow the command [Even though acknowledges command then does nothing] or doesn't understand-- Google Assistant is more flexible, you need to be more precise when giving commands to Alexa [Even with music, asking her to play something such as Day Oh by Harry Belefonte is not on there but the other name Banana Boat is] . I prefer Google Assistant on my phone for and considering Google Home but I hate google because they are a shady ass company, as if Amazon is much better though.

I talk Crap about Alexa but I still like her. She is useful if you can get the commands right and deal with the frustration of trying to phrase something in order to get the right answer.