I don’t have a Sub 4, but by all accounts there is marginal difference in bass produced when comparing Sub (Gen3) and Sub 4.
The fact Sonos allows a dual Sub setup incorporating both Sub (Gen3) and Sub 4 further demonstrates that there is no dramatic sound difference between the two Sub versions, otherwise they wouldn’t allow it to be supported configuration.
A dual Sub setup can be beneficial as it can even out the bass response in a room. However, if you’re happy with the performance of your single Sub (Gen3) as it is, there’s no compelling reason to purchase a Sub 4. I certainly wouldn’t replace a Sub (Gen3) with a Sub 4 at present. I’d rather spend the funds placing speakers in other rooms.
Ok, thank you…
What about this problem?
Sonos have replied on that thread to say that particular issue is considered as resolved.
Can't address the Sub 3, but I can't tell the difference in my Sub 2s and my Sub 4. I sure wouldn't replace any of the 2s with 4s unless it was required for something I really wanted.
Got in a which Sub to buy, a 3 or 4 and some good points were made for the 3 due to the lower cost.