Will I need to add a second boost ?

Where are you hearing the delay? Is it from the 3 bedroom speakers, when you're playing the TV? That would be normal. You shouldn't, however, be hearing any delay from any of the speakers when playing just music (not on the TV).

The Playbar communicates with the surround speakers and the sub using the 5GHz frequency, which is quicker, but more fragile (i.e. doesn't do well going through walls). It takes the digital input from the TV directly, without any processing, so that it can be as close to "lip sync" as possible. However, if you're pushing that same data through to the other 3 speakers, they'd be on the 2.4 Ghz band, and the Playbar (or whatever root device you have) would be doing a little bit of buffering in order to make sure that the stream gets through properly, without interruption. That approximately 70ms may be the "delay" you're hearing.

At least, that's my understanding of the way it works. Always open to correction from board members with more knowledge than I.

Is there a way to avoid it ? I will double check the settings of the boost. Thanks alot

Not really, to my knowledge, no. I occasionally push my TV sound to my kitchen where I've got a pair of Play:1s, and I just group them, and turn down the volume on the Playbar.

It's a function of Sonos being full home speakers. There has to be a certain amount of buffering when using the 2.4GHz band in order to make sure that all devices can get and play the same data at the same time. You're just running in to the bugaboo of the Playbar, which is a slightly different beast than the normal speakers, due to the digital connection and the 5GHz communication.

Thanks alot. It isnt earth shattering nor will i ever consider returning this great product !!!!!

I agree. Inconvenient, but once you understand the physics/design limitations behind it, it's easily accepted. And I agree, outstanding product. I may have about 18 of them in my home 🙂