I’m not quite sure I understand your post, or concerns here? You can continue to use the Connect:Amp with the S1 Sonos App and Deezer. …Then also use your new Roam with the S2 Sonos App and Deezer aswell, but ‘perhaps’ just not at the same time, but that’s if the Deezer service ‘may’ limit you to one stream at a time only, but maybe try it and see if it works with multiple concurrent streams. Other than that, Deezer should work fine with both your S1 & S2 Systems. 
(NB: I’m assuming your Connect:Amp is not S2 compatible in my post above.)

Hi Ken, and thank you for your answer. Should I define two different systems connected to the same sonos account (and the same deezer account as well)?

I assume it’s impossible for me to use a single app for my two devices, I will have to consider them as if they were two different brands devices..

ps: how could I know if my connect:amp is S2 compatible (I tried to use it on the app but it dodnt work, not sure of what I should do..)

Yes, the same Sonos account (email/password) for both S1/S2 Apps is fine to use, or you can, if you prefer, use different accounts, that’s entirely up-to you. In my case I use the same account.… Then you just need the one Deezer account to add the Deezer (subscription account) for both systems.

To discover if your Connect:Amp is only S1 compatible, check your ‘System’ tab in your online Sonos profile - it should show there which system the device is compatible with. See link:
https://www.sonos.com/en-us/myaccount/system/households/devices

edit: Also see this support document for device compatibility:

https://support.sonos.com/en-us/article/sonos-s2-compatibility

@FloMB,

• Connect:Amp (gen1) - (S1 only) are those devices manufactured between October 2008 —> March 2015
• Connect:Amp (gen2) - (S1/S2 compatible) are those devices manufactured March 2015 onwards.

The first 4 digits before the serial number on the device label is the year and month of manufacture (Example: 1608C is August 2016)

Hope that assists too.