They have minor cosmetic differences (trim color and different Join button). The Gen 3 also has updated internals and is only compatible with the S2 app. But they both sound the same.

Excuse me for hi-jacking this thread but I often see Sonos Subs on a  particular auction site and very attractive prices but they dont always state which Gen they are. Would a Gen Sub 1 work on the S2 app? I currently have an Arc, Era 300. Plus two 3’s and a play one which are earlier Gens?

All Subs work on S2.  Only Gen 1 and Gen 2 Subs work on S1

Also if you want to have two sub on a Home Theater set up one of the subs MUST be an S3

Sonos has offered me a 15% discount to upgrade my Sub to a Gen 3. I have to wonder why? What will I gain in performance by spending, essentially, $700?

@kayakor 
 

the ability to have Dual Subs in that room or a second room with a Sub

it serves no benefit for you as a direct replacement 

Or a small discount on a Sub for another room?

Thank you.

Can anyone help me please.??  I have a sub which I brought in 2019 which is the second generation but since this new update I cannot connect it to my Sonos system .

When this new update came my Sonos s2 app has gone and I now have trouble to even find my speakers. The s2 app gave the option (find missing product) but this new app will not even pick up my sub it’s has if I never had one .

I have tried everything to try and fix it but without it even picking the sub up I cannot connect it.

I only found this page by accident so I’m not sure if I will be able to find it again.

I am not good with technology has I had a friend to fix it for any other time but he sadly passed on.