The Sonos adapter is analog to USB, and the generic adapters are USB to analog and won’t work.  As to quality, the conversion is standard Nyquist-Shannon, which states for all signals ½ the sampling rate, the signal is reproduced exactly the same as the analog input.  Since the sampling rate is 44 KHz, and no human can hear anything above 20 kHz, the signal will be indistinguishable from the original.  Audiophiles will disagree with that, but audiophiles have no clue, and are prone to falling for snake oil. 

A few things to be said here.

First, neither the Five or Era 100 are designed to be used with your TV.  By that I mean that they have a built in delay when playing audio to allow for proper wireless multiroom audio streaming.  You’re likely to see lip sync issues.  

Second, the Sonos adapter converts analog audio to digital.  The Amazon adapter your seeing probably converts digital to analog...they are not the same thing.  To my knowledge, no one but Sonos sells an analog to digital convertor dongle.

Third, the Era 100 has bluetooth and the Five does not, and if you want to try playing TV audio, that is probably the better way to go.  I’ve done this with an Era 300 and found that the delay is not that noticeable.  However, I rarely use the TV it’s connected to, and never for any real ‘serious’ TV watching, so it’s fine for my use case.

As far as which one I would recommend, the room size factors in more so that what type of music you listen to.  I do not have the Era 100 personally, but find the Sonos One (similar) is great for small, mid sized rooms, particularly when adding a sub.  The Five is needed for large spaces.  That said, I might consider the Era 300 with sub if I was into electron music due to the atmos music capabilities.  I’m not sure if much of your preferred genre is recorded in atmos just yet, but it seems like atmos would enhance it greatly.

Thanks for the clarification, I will definitely buy the adapter from Sonos website instead of Amazon then!

Sorry for the bluetooth on the Five I thought it was compatible, I understand these speakers are not designed to be used with TV directly anyway but if you say it’s barely noticeable I think I’ll give a try and see how it goes..

I’m not really looking TV so there’s no dialogue, it’s all about music (DJ Sets)

Otherwise if it’s a big issue, I think I will consider the option you gave me on the other topic which is to buy the SONOS AMP.

If I have to buy the Sonos amp:

• Can you confirm the lip Sync won’t be an issue anymore ?
• Do you recommend to buy different speakers from another brand for example or the ERA 100 will do just fine ? (I like the fact that the Sonos are designed and small but if you have other suggestions i’m happy to know)

Regarding the type of music I listen, yes it’s electronic but it’s more underground stuff like Techno or Trance so there’s literally no Atmos content and I don’t want any spatialization effect anyway so ERA 300 is out of my scope.

I just want a proper and clear sound quality from speakers with deep basses from the sub (i’ll probably get the mini or 3rd gen, don’t know yet)

Yes, the Sonos amp has an HDMI-ARC port and will play audio immediately for devices connected to the port, same as Sonos soundbars.  I 

The Sonos Amp should be used with passive speakers.  I like JBL speakers, but I can’t say I’ve done a lot of research or know what’s best for different situations.  The Era 100 is an active, with the amp built into the speaker.  You can’t wire an Era 100 to a Sonos amp like you can a passive speaker.  You can connect the wirelessly, but the Era 100 would be playing the role of surround sound speakers, or a different sonos room (with delay when playing TV audio).  In short, get a pair of 3rd party passive speakers.

If you purchase the Amp, you must use 3rd party passive speakers.  You cannot use the Era 100’s with the Amp.  You could group them with the Amp, but that will give the same delay as if you connected them via the Line-In.

Ok I understand now! And from what I read, passive speakers doesn’t require to be plugged to AC right ? Only a wire to the AMP ?

Correct.  Two leads, + and -.

Another thing in my mind :

Will the sound quality be different and noticeable (except the lip sync issue) when playing from Line-In source (YouTube on TV) rather than Spotify or Bluetooth (the way it’s designed to be used) ? Or it’s basically the same

Depends.  Most YouTube content is 2 channel stereo, so there won’t be much of a difference.  But it all depends on the quality of the recording, and some YouTube content is horribly recorded. 

I found these passive speakers which looks nice but it seems to be for exterior usage

https://www.bowerswilkins.com/fr-fr/product/integrated-solutions/am-1

In terms of performance what is the difference ? It couldn’t fit in a living room ?

I’m kinda desesperate finding passive speakers small like ERA 100 or Sonos 5 but I feel like it’s impossible 

Yes, those are designed for outdoors.  You can use them, but not ideal.  Look for bookshelf speakers.

Here is a good place to look at bookshelf speakers, you might buy elsewhere if you find a better price.

$69 to $7000, don’t go wild!

https://www.crutchfield.com/g_37900/Bookshelf-Speakers.html

Speaker designs sound different from each other and you are allowed to prefer one vs another. One way to think about it is that the speaker designer designs speakers to match his favorite seat in the auditorium. If that is your favorite spot too, then you like his speakers. If you move around in the auditorium the sound varies quite a lot and you will not enjoy speakers designed to match another seat.

My friends and I don’t usually prefer the same speakers, but we respect each other’s choices. Actually, I have moods. I might prefer one speaker for full classical orchestra and another for thumping rock-n-roll.