No, it isn’t necessary. The Play:5 (Gen 2) alone has sufficient bass. You would be better off using the money to get a second Play:5 to create a stereo pair.

The older Play 5, gen 1 is S1 only so you might want to pass on that.

The Play 5 gen 2 is newer but we are seeing a number of users with WiFi card issues recently. I still use one of these daily.

I’d really suggest a current Sonos Five.

I’ve had both Older Play 5s and I didn’t feel the need for a Sub with either.

Get the new Five (used if you have to) and skip the Sub. A second Five as suggested above would give you more sound improvement.

Thankyou